IRLF ENGIN. LIBRARY B 3 1EM CON Lesley Bruce & Banning New York TX OF C/ LIBRABY OF CIVIL Gift of Mrs, Edv/in H. Warner from her husband's library, January 1928 Lngineerinfir T it-..r.>,. UNIVERSITY OF CAOTORNIA fc& AIVIMENT OF CIVIl- ENGINEE^ttfcl UNIVERSITY or CALIFORNIA ^WPARTMENT OF CIVTL ENQIMEERttW BERKELEY. CALIFORNIA I- 1 * THE HIGHEST COMPLETE CONCRETE BUILDING IN PHILADELPHIA; PLANT OF THE KETTER- LINUS LITHOGRAPHIC MANUFACTURING COMPANY CONCRETE FACTORIES An illustrated review of the principles of construc- tion of reinforced concrete buildings , includ- ing reports of the Sub-Committee on Tests , the U. S. Geological Sur- vey and the French Rules on Re i nfo reed Concrete COMPILED By ROBERT W. LESLEY, Associate Am. Soc. C. E. Published for the CEMENT AGE COMPANY, By BRUCE & BANNING, New York. Engineering Library TABLE OF CONTENTS Concrete Plant of the Ketterlinus Litho- graphic Manufacturing Co. . Frontispiece Introduction ...... 6 Report of the Sub-Committee on Tests . 10 United States Advisory Board on Fuels and Structural Materials . . . -19 French Rules on Reinforced Concrete . 27 Reinforced Concrete Construction . . 42 Concrete in Factory Construction . ..7.1 A Surface Finish for Concrete . . . 103 Value of Concrete as a Structural Material . 112 Miscellaneous Illustrations . . . 133 785318 INTRODUCTION The subject of concrete and reinforced concrete is one of the most important matters that is now before the American public. So im- portant has it been considered by those connected with engineering, that the leading societies in this field have associated themselves in the creation of a Joint Committee on Concrete and Reinforced Concrete, the members of which Committee are representatives of the following- societies : American Society of Civil Engineers; American Society for Testing Materials; American Railway Engineering & Maintenance of Way Association, Association of American Portland Cement Manufacturers. In addition to this, the following organizations are lending their hearty co-operation in the work. National Board of Fire Underwriters; National Fire Protection Association ; The Concrete Block Machine Manufacturers Association, and the National Association of Cement Users. The Work of the Committees This Committee on Concrete and Reinforced Concrete, as is well known, has been at work for nearly two years endeavoring to arrive at some definite conclusions on the important subjects entrusted to their care. It has been most fortunate in being able to secure, not only the co-operation of the leading colleges of the United States in its research investigations, but also the co-operation of the United States Advisory Board on Fuels and Structural Materials, which has a splendidly equipped laboratory at St. Louis. The importance of the work was recognized by the United States Government in a practical way by an appropriation of one hundred thousand dollars, for the purpose of carrying on the experiments required. The scope of the work is fully detailed in the report of the Sub Committee on. Tests which, with its introductory matter, fully explains the field to be covered, the purpose of the investigations, and gives with great accuracy the subjects to be investigated in the line of concrete and reinforced concrete. [6] INTRODUCTION This has been followed within a recent period, by the adoption by the Advisory Board on Structural Materials of the U. S. Geological Survey of a program for a full investigation of cement blocks, thus covering in the investigations to be carried on at the Government laboratory at St. Louis the two great fields of practical use to the community at large. It is needless to say that the program involves a long period in its accomplishments involves practical research and investigation into the subject in all its details, beginning with the selection of cements, the sands and the aggregates, and going through the whole field of the methods of constructing block monolithic and reinforced concrete structures. The examinations into the making of beams of various characters; into the making of columns; into the proper methods of reinforcing these forms of construction and finally, the investigation into cement blocks covers a large field and is but a beginning. It is hoped that when proper formulae have been arrived at in all these various branches of the art, that such a standard for concrete and reinforced concrete and cement block construction will have been developed, that building inspectors all ov^r the country and leading engineers in all parts of the United States will adopt and put in force the methods suggested. These methods, however, will necessarily be accompanied by the outline of a plan to secure the proper inspection of the structures to be erected, thus securing through the work of the committee and of the National Advisory Board, absolute standardiza- tion of concrete and reinforced concrete and cement block construction, subject to the most approved methods and the most rigid inspection. The National Advisory Board on Fuels and Structural Materials held a meeting in Washington in December, where the work of the laboratory was presented in a brief way, and where it was shown that there are now under construction at the St. Louis Laboratory more beams, girders and columns than hitherto have been made in laboratory work in the United States, so far as official records show. The investigations into sands and aggregates are also on the largest possible scale, and at the Government Laboratory at St. Louis to-day there are at least fifty men employed in the work, and after the first of the year it is expected that this number will be increased to one hundred, the purpose being to secure in the shortest possible time, the fullest, clearest and most definite results. French Rules on Reinforced Concrete In connection with this work, the Committee of the Engineering Socie- ties on Concrete and Reinforced Concrete had before them at their last meeting in New York on the T3th of December, 1906, the French Rules on Reinforced Concrete which were published in the November number of CKMEXT AGE. The work of the French Committee was highly appreciated by the Joint Committee and the brief, succinct and careful way in which they arrived at their results was greatly praised. [7-3 REINFORCED CONCRETE The work of nearly four years, of a Committee comprising leading French engineers both in civil life and government service and leading French experts on concrete and cement the report of the French Committee is deserving of the highest commendation and will no doubt be of great use in clearing much of the brush away on many subjects now before the American Joint Committee and the National Advisory Board. These Rules are published in this volume for the purpose of giving the public, at the present time, the methods governing reinforced concrete in the nation which was among the pioneer nations to use this form of construction a nation which ten or fifteen years ago was in the forefront of reinforced concrete work and which is to-day doing work on the most approved lines and of the greatest importance. With such a system as is advocated under these Rules, or with such systems as will no doubt be recommended by our own Advisory Board and our United States American Joint Committee of Engineering Societies on Concrete and Reinforced Concrete it will be possible to secure work of per- manence, strength and uniformity in this important art of concrete construc- tion. Following these French Rules will be found descriptions of various systems of reinforced concrete used by leading concerns making a spec- ialty of this form of construction. They embrace a number of systems that have been in use many years and with which much good work, under the most practical methods, has been produced. The results of the work done by many of the companies having these var- ious systems for reinforcing concrete, is shown in the following article on con- crete in factory construction. This article is one of the most complete ever prepared on this important subject and is replete with descriptions of many prominent factory buildings and is illustrated by photogravures of the work done in the line of manufacturing establishments in all parts of the country, including every type of manufacturing business. The Surface Finish of Concrete While the illustrations do not show the beauties that can be developed in the surface finish for concrete, the fact that this material is adaptable and can receive a beautiful architectural finish is shown by Mr. Quimby's article on the Surface Finish for Concrete. The illustrations which accompany this brief communication are so beautiful as to have created general interest in engineering and architectural circles everywhere, both in this country and abroad. They show what can be done with a material that has hitherto been supposed to represent a plain gray surface, without shadow and without light, and how beautiful concrete can be made when properly used and when pro- perly finished. The Views of Leading Engineers and Architects A symposium, representing the views of leading engineers, architects and experts in the field of concrete and reinforced concrete, is a proper [8] INTRODUCTION conclusion to such a volume as this. That this new building material, which certainly is destined to take the place of lumber, brick and stone con- struction in our country, should attract the attention of the leading minds in engineering and architectural circles, was but the natural result of the importance that it is attracting in the building world, and that these opinions collated from many sources and representing many varying views, should unanimously agree on the value, importance, durability and permanence of concrete and reinforced concrete construction, naturally follows the growth and the success of this new building material. While this little volume is not intended to be used or considered as authoritative in the field that it sets out to cover, it is however believed to embrace much that is of interest and much that is valuable in the way of information on the present state of the art of concrete and reinforced con- struction; and if it sets many new minds thinking on this important sub- ject, and leads many new minds to better methods, better inspection, better care in the work, "the purpose of this little volume will have been accom- plished and the country at large will certainly be benefited. ROBERT W. LESLEY, Associate Am. Soc. C. E. REPORT OF THE SUB-COM- MITTEE ON TESTS Made to the Joint Committee on Concrete and Rein- forced Concrete; affiliated Committees of Am. Soc. C. E.j Am. Soc. for Testing Materials, Am. Ry. Engineering and Maintenance of W^ay Ass. and the Assoc. of Am. Portland Cement Manufacturers. In compliance with the resolution adopted by the Joint Committee on Concrete and Reinforced Concrete at the meeting held in New York on October n, 1905, your Committee on Tests desires to present the following report as to the policy to govern the future work of the Joint Committee, to- gether with a program of the investigation they propose making, with sub- divisions, and the plan of execution. The Joint Committee on Concrete and Reinforced Concrete was appointed, primarily, for the purpose of providing through the various Societies represented definite information concerning the properties of con- crete and reinforced concrete, and to recommend factors and formulae required in the design of structures in which this material is used. While the Joint Committee has thus far accomplished little toward formulating a report, it has, nevertheless, acquired a definite knowledge of the work such a report demands. The tests made prior to the appointment of the Committee were scattered and somewhat fragmentary, and while yielding information of considerable value, the limited scope of the work, lack of uniformity of conditions, and methods, and failure to properly report details concerning tests or to complete the investigations, render the results insufficient for the formulation of a report. The Committee, therefore, decided that it was desirable to conduct tests along certain lines. Until recently the only channels open to the Committee for conducting such investigations were the laboratories of the technological institutions and, perhaps, a few others. At the meeting of the Joint Committee held during the international Engineering Congress at the World's Fair, St. Louis, in October, 1904, the Committee on Tests was instructed to inaugurate investigations at such technological institutions and other laboratories possessing the requisite facilities as would undertake the work. Accordingly, during the last school year, tests were made under this Committee's direction in the laboratories of some twelve engineering schools. The results have been reported to the Committee on Tests, and the compilation is nearly ready for presentation to the Joint Committee. The plan adopted bv the Joint Committee involve* direction and inspection of this work by the committee on Tests. This the [TO] REPORT OF THE SUB-COMMITTEE OX TESTS Committee was unable to do through lack of funds with which to pay the expenses of inspectors and other assistants. It might also be stated that the first year's work would naturally be of a preliminary nature, which would serve to develop essential points to be observed and the provisions to be made in future tests. Naturally, the conditions under which these tests were made, and the personal equa- tions of those making the test pieces, and the ideas of those supervising the tests, were widely at variance, and the results, while possessing value, ar not fully comparable and must be studied individually. , About March of the present year a small appropriation was made to the United States Geological Survey for the investigation of structural materials. In the determination of the manner in which this money should be expended it was deemed advisable to create for the purpose a National Advisory Board on Fuels and Structural Materials. A number of the members of the Joint Committee were appointed members of this Advisory Board, and through their influence the money was devoted to the investi- gation of cement mortars and concretes. At the meeting of the Joint Committee in Cleveland, on June 21, 1905, it was decided to co-operate with the United States Geological Survey, and the Committee's representatives on the Government Advisory Board were requested to advise as to the plan for this cooperation. At the meeting of the Committee held at Atlantic City, on June 30, 1905, a formal plan of cooperation was adopted by which the program of the Committee on Tests was to be carried out in the Government labora- tories. These laboratories, known as the "Structural Materials Testing Laboratories," have been organized and are under the direction and super- vision of the present Chairman of the Committee on Tests. It was also decided to conduct the investigations at such institutions as the Committee on Tests might elect, under the direction of the Committee and the inspec- tion of the representative of the Government laboratories. Accordingly, ar- rangements have been made for carrying on tests at the Universities of Illi- . nois, Purdue and Wisconsin and, possibly Columbia. These tests consist of determinations of the effect, at different ages, of varying percentages of round, square and flat bars of steel of different elastic limit, using the same concrete; of the bond under similar conditions; of the properties' of tee- beams ; of the effect of loading beams centrally, and at 2, 4 and 8 points : of the shearing strength of concrete; of the tensile strength and modulus of elasticity of concrete in tension in length of 12 feet; of the effect of different methods of reinforcing a beam for diagonal tension. Policy of Committee The policy of the Joint Committee, up to the present time, has lacked definiteness. It is evident that, to secure efficiency the Committee must adopt a policy to govern its future work. REINFORCED CONCRETE It is apparent that it would be desirable to conduct a comprehensive series of experiments in one laboratory where the conditions, methods and personal equations of those making the test pieces and the ideas of those supervising the tests are more nearly constant. Thus comparable results would be obtained, giving the uniformity and consistency necessary for the development of essential underlying principles, and which could not be expected under the conditions prevailing at different places and under the guidance of different persons, as would be the case at different technological institutions. The Committee would, by this means, obtain ultimately, as a basis for its report, a complete and thorough series of tests made by the same squa< of experienced observers acting under the direct supervision of those having both the ability to judge of the thoroughness and reliability of tin work and the necessary time to devote to its supervision. The wide area over which the technical schools are scattered renders the expense of providing uniform materials and of inspecting the prepara tion of the test pieces and the execution of tests very great. Besides, the work cannot generally be carried on uniformly throughout the year, but must be concentrated into a few months. This is a serious difficulty in any series of tests. However, in the progress of these investigations, there will necessarily be considerable experimental work in opening up certain phases of a prob- lem, as, for example, the study of proper methods to be followed, sources of error to be guarded against, the probable cause of a given phenomenon, that would be of material help in planning the work, or in corroborating the results of other tests ; and it would seem wise to secure the cooperation of the technical schools, utilizing their faculties to the extent indicated, in carrying on investigations. The entire Joint Committee has been divided into a number of sub- committees for the purpose of collating existing literature and the result of previous investigations. These results, when compiled, will serve, wit" the recommendation of each Committee, as a guide in formulating the future work of the Joint Committee. The results of the compilations oi the various sub-committees shall be turned over to the Committee on Tests for their consideration and to be reported by them to the Joint Committee If it is found that there is a reasonable concordance in certain lines, i would seem undesirable for the Committee on Tests to plan more than a few confirmatory experiments. In those lines where there is no agreement, the Committee work must necessarily be more extensive in order to be con- clusive. The following is a suggested program of the investigations to be made by the Joint Committee, from which a schedule is to be prepared as the tests progress: [12]" REPORT OF THE SUB-COMMITTEE OX TESTS Proposed Program for the investigation of Concrete and Reinforced Concrete* I. Examination and Classification of Constituent Materials: Sands, gravels, stones, gravel and stone screenings (^4 -inch screen), slags cinders, etc., to be collected by a special representative of the Testing Labora- tory sent out for that purpose. A. EXAMINATION OF DEPOSIT as to the extent and nature of the material from which the samples are collected. B. PHYSICAL TESTS IN THE LABORATORY I .... 1. Mineralogical examination, 2. Specific gravity, 3. Weight per cubic foot, 4. Sifting (granularmetric composition), 5. Percentage of silt and character of same, 6. Percentage of voids, 7. Character of stone as to percentage of absorption, porosity, permeability, compressive strength and behavior under treat- ment. C. CHEMICAL ANALYSIS as to the character of the stone, silt, etc., used in tests. //. Tests and Classification of Mortars: made with Typical Portland Cement and sand, gravel and stone screenings (^-inch screen). Proportions to be stated by weight and volume. Unit of volume for cement, 100 Ibs. per cubic foot. The typical Portland cement to be prepared by thoroughly mixing a number of brands, each of which must meet the following requirements: Specific gravity, not less than 3.10. Fineness, residue not more than 8% on No. 100 or 25% on No 200 sieve. Time of setting: Initial set, not less than 30 minutes; Hard set, not less than i hour or more than 10 hours. Tensile strength : Neat, 24 hours in moist air, I75lbs. 7 days (i day in moist air, 6 days in water) 5oolbs 28 days (iday in moist air, 27 days in water) 6oolbs. ^Approved by National Advisory Board on Fuels and Structural Materials at the meet- ing held at Washington, D. C., March 3 ist, 1906. One part cement, 3 parts standard sand : 7 days (i day in moist air, 6 days in water) I75lbs. 28 days (i day in moist air, 27 days in water) 25olbs. [13] REINFORCED CONCRETE Constancy of volume : Pats of neat cement 3 inches in diameter, j/2-inch thick at center, tapering to a thin edge, shall be kept in moist air for a period of 24 hours : A. A pat is kept in air at normal temperature and observed at intervals for at least 28 days. B. Another pat is kept in water maintained as near 70 deg. F. as practicable and observed at intervals for at least 28 days. c. A third pat is exposed in an atmosphere of steam above boiling water in a loosely closed vessel for 5 hours. These pats must remain firm and hard and show no signs of distor- tion, checking, cracking or disfiguration. The cement shall not contain more than 1.7$% Anhydrous sulphuric acid or more than 4% magnesium oxide. A test of the neat cement must be made with each mortar series for for comparison of the quality of the typical Portland cement. A. PHYSICAL TKSTS IN LABORATORY : 1. Tensile strength with one part cement to varying percentages of material under test, for 7, 28, 90, 180 and 360 days ; 2. Compressive strength with one part cement to varying percent- ages of material under test, for 7, 28, 90, 180 and 360' days; 3. Transverse strength with one part cement to varying percent- ages of material under test, for 7, 28, 90, 180 and 360 days; 4. Shearing strength with one part cement to varying percent- ages of material under test, for 7, 28, 90, 180 and 360 days ; 5. Tensile strength with cement, material sieved to one size, for 7, 28, 90, 180 and 360 days; 6. Compressive strength with cement, material sieved to one size, for 7, 28, 90, 180 and 360 days; 7. Transverse strength with cement, material sieved to one size, for 7, 28, 90, 1 80 and 360 days ; 8. Shearing strength with cement, material sieved to one size, for 7, 28, 90, 1 80 and 360 days ; 9. Modulus of elasticity in compression of different mixtures as to proportion and size of the aggregate, for 30. 90, 180 and 360 days ; [14] .REPORT OF THE SUB-COMMITTEE O\ TESTS 10. Modulus of elasticity in tension of different mixtures as to proportion and size of aggregate, for 30, 90, 180 and 360 days ; 11. Yield in mortar; 12. Porosity; 13. Permeability; 14. Volumetric changes in setting ; 15. Absorption; 16. Methods of waterproofing; 17. Freezing tests; 1 8. Coefficient of expansion ; 19. Effect of oil: (a) On hardening mortar, (b) On hardened mortar; 20. Effect of sea water. ///. Tests and Classification of Concrete: made with typical Portland cement and sand, gravel and stone screenings ings, gravel, sand, cinder, slags, etc. Proportions to be stated by weight and volume. Unit of volume for cement, 100 Ibs. per cubic foot. A. PHYSICAL TESTS IN LABORATORY : 1. Tensile strength with different mixtures as to proportion and size of the aggregate, for 30, 90, 180 and 360 days ; 2. Compressive strength of different mixtures as to proportion and size of the aggregate, for 30, 90, 180 and 360 days; 3. Transverse strength of different mixtures as to proportion and size of the aggregate, for 30, 90, 180 and 360 days; 4. Shearing strength with different mixtures as to proportion and size of the aggregate, for 30, 90, 180 and 360 days; 5. Modulus of elasticity in compression of different mixtures as to proportion and size of aggregate, for 30, 90, 180 and 360 days; 6. Modulus of elasticity in tension of different mixture as to proportion and size of aggregate, for 30. 90, 180 and 360 days ; 7. Character crushed stone used : (a) Weight per cubic foot, (b) Size, (c) Percentage of voids, fd) Percentage of silt: 8. Weight per cubic foot, uncrushed : 9. Yield ; 10. Absorption ; 11. Porosity; 12. Permeability; [15] REINFORCED CONCRETE 13. Methods of waterproofing; 14. Protective influence against corrosion of metal; 15. Fire resisting qualities: (a) Effect of heat on hardening concrete, (b) Effect of heat on hardened concrete, (c) Thickness necessary for proper insulation. 1 6. Freezing tests ; 17. Volumetric changes; 18. Effect of vibration and of applied stress (impact) ; (a) On a hardening of a plain and reinforced concrete, (b) On hardened plain and reinforced concrete; 19. Adhesion of concrete to metal under varying conditions, for varying periods, up to at least three years : : (a) Effect of shape, (b) Effect of embedded length, (c) Effect of various kinds of loading, (d) Effect of chemical action, (e) Relative value of surface adhesive resistance and grip; 20. Effect of oils: (a) On hardening concrete, (b) On hardened concrete; 21. Coefficient of expansion; 22. Effect of sea water. B. FULL SIZE TESTS: 1. Beams of various spans, sections and compositions; 2. Building blocks and bricks, as to: (a) Compressive strength, wet and dry mixtures, (b) Transverse strength, wet and dry mixtures, (c) Shearing strength, wet and dry mixtures, (d) Absorption, wet and dry mixtures, (e) Permeability, (f) Methods of Waterproofing, (g) Effect of accelerating the hardening of concrete blocks by means of live steam, etc., (h) Fire resisting qualities, (i) EfHorescence. IV. Tests of Reinforced Concrete: A. BEAMS : 1. Effect of amount of reinforcement, 2. Effect of character of reinforcement, 3. Effect of form, size, and position of reinforcing bars, 4. Effect of initial stress in reinforcement, 5. Effect of different manners of loading, 6. Methods of providing for diagonal stresses, [16] REPORT OF THE SUB-COMMITTEE O\ TESTS 7. Effect of variation in section, such as trapezoidal, tee-shaped, etc., 8. Effect of variation in length and depth, 9. Effect of restraining the ends, 10. Effect of repetitive loading. B. COLUMNS: 1. Effect of amount of reinforcement, 2. Effect of disposition of reinforcement : (a) Longitudinal, (b) Hooped, (c) Combination of (a) and (b), 3. Effect of form, size, and position of reinforcement, . 4. Effect of character and eccentricity of loading, 5. Effect of variation in section, such as square, round and rectangular, 6. Effect of fixing the ends, c. SLABS : 1. Supported at two or four edges, 2. Eixed at two or four edges, 3. Use of expanded metal, wires, etc., 4. Effect of concentration of load, 5. Variation in per cent, of reinforcement, 6. Variation in span and thickness. D. ARCHES : 1. Continuous ring, 2. Hinged, 3. Voussoirs, 4 Shape, 5. Span and rise. As regards the work in the technological institutions, it is recommended that there be taken up, in a limited number of schools possessing the proper facilities, investigations comprising, in part, tests in which the methods of execution are still open to formulation and which involve general phe- nomena. In addition to this, it is recommended that the Committee on Tests be authorized to offer its services in an advisory capacity to any laboratory conducting investigations of this character. The following list is suggested as available at present : 1. Shearing, Comparison of methods; 2. Modulus of elasticity, Comparison of methods ; 3. Protective influence of concrete against corrosion ; 4. Fire resisting qualities of concrete; 5. Methods of waterproofing; 6. Coefficient of expansion ; 7. Effect of vibration and applied stress ; 8. Adhesion of concrete to metal ; [17] REINFORCED CONCRETE 9. Reinforced concrete beams : (a) Effect of different manners of loading, (b) Methods of providing for diagonal stresses, (c) Effect of variation in section, (d) Effect of restraining ends, (e) Amount and character of reinforcement; 10. Reinforced concrete columns, Method of testing. The direction of all this work is to be under the Committee on Tests, as provided in the rules of organization. Summary of Recommendations The foiling is a summary of recommendations: 1. A comprehensive series of tests to be conducted under the direction of the Committee on Tests at some point in in cooperation with the United States Geological Survey. 2. The cooperation of the technological schools in tentative or general experimental work under the direction of the Committee on Tests. 3. The collation of existing literature and results of previous experiments by sub-committees of the Joint Committee, to be reported to the Committee on Tests for its con- sideration, and to be reported by them to the Joint Committee. The Committee on Tests has endeavored to outline a definite policy from which it may reasonably expected to derive the requisite data for the formulation of its final report. Each member of the Joint Committee should be willing to render all possible assistance in carrying out the program, and the Committee on Tests would further emphasize the fact that, unless the Joint Committee takes hold of the work in a vigorous manner and provides ample funds for the purpose, the Joint Committee had better be disbanded. The Committee on Tests cannot emphasize too strongly the vital importance to the engineering profession of the results to be derived if the program proposed be carried out in an efficient manner. Submitted by the Committee on Tests. RICHARD L. HUMPHREY, Chairman. Committee on Tests, RICHARD L. HUMPHREY, . A. N. TALBOT, W. K. HATT, OLAF HOFF, GEORGE F. SWAIN, SPENCER B. NEWBERRY. [18]. UNITED STATES ADVIS- ORY BOARD ON FUEL AND STRUCTURAL MATERIALS ( United States Geological Survey) The Structural Materials Testing Laboratories In- vestigation of Mortar and Concrete Building Blocks I Variables entering in the manufacture of blocks under investigation. A. Type of Wall Block all plain face and standard ends. (i) With facing (a) One piece Wall Block, i. Hollow block. (a) Down face. (x) Single air space, (y) Double air space, (b) Side face, (x) Single air space, (y) Double air space, 2. Solid block, (a) Down face. (b) Side face. (b) Two piece wall block. (a) With metallic Bond. (b) Without metallic Bond. (2) Without facing. (a) One piece wall block. T. Hollow Block (a) Down face. (x) Single air space, (y) Double air space, (b) Side face. (x) Single air space, (y) Double air space. !\> 111 \FORCED CONCRETE * c * '2.* ' Solid btocfc/* . (a) Down face, (b) Side face, (b) Two piece wall black solid face. (a) With metallic bond. (b) With metallic bond. B. Materials Used. 1. Cement. Typical Portland. 2. Aggregate. (a) Single. 1. Sand. 2. Limestone. 3. Granite. 4. Gravel. 5. Cinder. (b) Double, consisting of sand and 1. Limestone. 2. Granite, 3. Gravel. 4. Cinder. c. Dimensions of Specimen. 1. Outside. (a) 8 x 8 x 16. (b) 9 x 12 x 24. 2. Web iy 2 " to 3". 3. Air space 30 to 33 1-3%. D. Consistency. 1. Damp. 2. Medium. 3. Wet. E. Proportions. 1. Mortar. (a) 1:2, (b) 1:4, (c) 1:8, (d) Balanced proportions for waterproofing. 2. Concrete. (a) 1:1:3. (b) 1:2:4. (c) 1:3:6. (d) Balanced proportions for waterproofing. [20] U. S. ADVISORY BOARD ON FUEL F. Process of Manufacturing. 1. Mising. (a) Hand. (b) Machine. 2. Molding. (a) Wet mixture cast in molds in which test pieces remain until hard set. (i.) Sand Molds. (a) Poured without vibration, (b) Poured witht vibration. (2.) Metal molds. (a) Poured without vibration. (b) Poured with vibration. (b) Damp and medium mixtures cast in molds from which specimens are removed before hard set. 1. Hand tamped. 2. Power tamped. (a) Air. (b) Mechanical. 1. Single application. 2. Repeated application. G. Curing. 1. Natural. (a) Air. (b) Air and sprinkling. 2. Artificial. (a) Submerging. (b) Steam. 1. Low pressure. (a) With CO2. (b) Without CO2. 2. High pressure. (a) With CA2. (b) Without CA2. H. Aging. 1. Blocks that are fired 60 days. 2. Blocks that are not fired. (a) 4 weeks. (b) 13 weeks. (c) 26 weeks. (d) 52 weeks. j. Use of waterproofing compounds, i. Applied to surface. REINFORCED CONCRETE 2. Added to material. (a) Body. (b) Facing. II Properties to be investigated. A. Strength. I. Transverse. (a) Type. (b) Material used. (c) Dimensions of specimens. (d) Consistency. (e) Proportions. (f) Process of manufacturing. (g) Curing, (h) Aging. (j) Use of waterproofing compound?. 2 Compression. (a) Type. (b) Material used. (c) Dimensions of specimens. (d) Consistency. (e) Proportions. Cf) Process of manufacturing. (g) Curing. (h) Aging. (j) Use of waterproofing compounds. 3 Shearing. (a) Type. (b) Material used. (c) Dimensions of specimens. (d) Consistency. (e) Proportions. (f) Process of manufacturing. (g) Curing, (h) Aging. (j) Use of waterproofing compounds. B. Permeability. (a) Type, (i) Block. (2) Special test piece. (b) Material used. (c) Dimensions of specimens. (d) Consistency. [22] U. S. ADVISORY BOARD ON FUEL (e) Proportions. (f) Process of manufacturing. (g) Curing, (h) Aging. (j) Use of waterproofing compounds, c. Absorption. (a) Type. (b) Material used. (c) Dimensions of specimens. (d) Consistency. (e) Proportions. (f) Process of manufacturing. (g) Curing. (j) Use of waterproofing compounds. D. Efflorescence. (a) Type. (b) Material used. (c) Dimensions of specimens. (e) Proportions. (f) Process of manufacturing. (g) Curing, (h) Aging. (j) Use of waterproofing compounds. E. Fire resisting properties. ( i ) Fired and Cooled in Air. (a) Type. (b) Material used. (c) Dimensions of specimens. (d) Consistency. (e) Proportions. (f) Process of manufacturing. (g) Curing, (h) Aging. (j) Use of waterproofing compounds. (2) Fired and cooled by spraying with water. (a) Type. (b) Material used. (c) Dimensions of specimens. (d) Consistency. (e) Proportions. (f) Process of manufacturing. (g) Curing, (h) Aging. (j) Use of waterproofing. [23] REINFORCED CONCRETE List of Members National Advisory Board on Fuel and Struc- tural Materials. From the American Institute of Mining Engineers: John Hays Hammond, Past-President, Empire Building, New York. Robert W. Hunt (of Robert W. Hunt & Co., Testing Engineers, Chi- cago, Pittsburg, and New York), Chicago, 111.; B. F. Bush, Manager and Vice-President, Western Coal and Mining Co., St. Louis, Mo. From the American Institute of Electrical Engineers : versity, New York ; Henry C. Scott, Superintendent Motive Power, Interborough Rapid Transit Co., New York. From the American Society of Civil Engineers : C .C. Schneider, President, Chairman Committee on Concrete and Rein- forced Concrete, Pennsylvania Building, Philadelphia,, Pa. ; George S. Webster, Chairman Committee on Cement Specifications, City Engineer, City Hall, Philadelphia, Pa. From theAmerican Society of Mechanical Engineers : W. F. M. Gross, Dean of the School of Engineering, Purdue Uni- versity, Lafayette, Indiana. ; Geoige H. Barrus, Steam Engineer, Pemberton Square, Boston, Mass.; P. W. Gates, 210 State Street, Chicago, 111. From the American Society for Testing Materials : Charles B. Dudley, President, Altoona, Pa. ; Robert W. Lesley, Vice-President, Pennsylvania Building, Philadel- phia, Pa. From the American Institute of Architects : George B. Post, Past-President, 33 East Seventeenth Street, New York. ; William S. Fames, Past-President, Lincoln Trust Building, St. Louis, Mo. From the American Railway Engineering and Maintenance of Way Asso- ciation : H. C. Kelley, President, Minneapolis, Minn. ; Julius Kruttschnitt, Director of Maintenance and Operation, Union Pa- cific Railway, 135 Adams Street, Chicago, 111.; Hunter McDonald, Past-President, Chief Engineer, Nashville, Chat- tanooga & St. Louis Railway, Nashville, Tenn. [24] U. S. ADVISORY BOARD OX FUEL From the American Railway Master Mechanics' Association: J. F. Deems, General Superintendent of Motive Power, New York Cen- tral Lines, New York ; A. W. Gibbs, General Superintendent of Motive Power, Pennsylvania Railroad, Altoona, Pa. From the American Foundrymen's Association : Richard Holdenke, Secretary, Watchung, N. J. From the Association of American Portland Cement Manufacturers : John B. Lober, President, Land Title Building, Philadelphia, Pa. From the Geological Society of America : Samuel Calvin, Professor of Geology, University of Iowa, Iow r a City, Iowa. ; I. C. White, State Geologist, Morgantown, W. Va. From the Iron and Steel Institute : Julian Kennedy, Metallurgical Engineer, Pittsburg, Pa. : C. S. Robinson, General Manager, Colorado Fuel Iron Co., Denver, Colo. From the National Association of Cement Users : Richard L Humphrey, President, St. Louis, Mo. From the National Board of Fire Underwriters: Chas. A. Hexamer, Chairman, Board of Consulting Experts, Bullitt Building, Philadelphia, Pa. From the National Brick Manufacturers' Association: John W. Sibley, Treasurer, Sibley-Menge Press Brick Co., Birmingham, Ala. ; Wm. D. Gates, American Terra Cotta & Ceramic Co., Chicago, 111. From the National Fire Protective Association : O. U. Crosby, Chairman Executive Committee, 76 William Street, New York. From the National Lumber Manufacturers' Association : Nelson W. McLord, President, Equitable Building, St. Louis, Mo.; John L. Kaul, President Southern Lumber Manufacturers' Associa- tion, Birmingham, Ala. [25] REINFORCED CONCRETE From the Corps of Engineers, U. S. Army : Lieut. Col. Wm. L. Marshall, Army Building, New York. From the Isthmian Canal Commission : Lieut. Col. O. H. Ernst, Washington, D. C. From the Bureau of Yards and Docks, U. S. Navy : Civil Engineer, Frank T. Chambers, Washington, D. C. From the Supervising Architect's Office, U. S. Treasury Department James K. Taylor, Supervising Architect, Washington, D. C. From the Reclamation Service, U. S. Interior Department: F. H. Xewell, Chief Engineer Washington, D. C. [26] FRENCH RULES ON REIN- FORCED CONCRETE A complete report of the official instructions just issued by the ministry of public works to govern the use of reinforced concrete in France Translated specially by CEMENT AGE. Copyright, 1996, by Robert W. Lesley, Phila. We present herewith a specially prepared translation of the important Instructions, /. f. Rules on Reinforced Concrete issued by the French Min- istry of Public Works, together with an explanatory circular of the highest possible interest. Without in any way, at this stage, commenting upon either the Rules or the Circular, we would emphasize what is indicated below, that this pub- lication is based upon the work of a special commission of some five years' standing, and upon the elaborate investigations conducted at the instance of that commission. If the Rules and the Circular do not in every zvay suit the conditions of design and workmanship beyond the borders of France, and thus cannot serve as a universal model, they nevertheless can serve as a skeleton upon which to base future requirements. As to our translation, it has been prepared by a French civil engineer of high standing, and revised by one of our most valued contributors, and if it lacks perfection it will not be for the want of care. To would-be users of this translation, we should perhaps sound a note of warning that we are protected by copyright (including the English copyright} but shall be happy to meet, as far as possible, any requests of would-be users, who may apply to us in writing for permission. THE popularity of reinforced concrete for structural work in France caused the French Government, as far back as 1901, to recognize the necessity of issuing data for the guidance of building owners generally and their own technical staff in particular. Thus the "Commission du Ciment Arme" came to be appointed in 1901 by the Ministre des Travaux Publics, (Public Works) with instructions to make enquiries and elaborate administrative rules to be applied in official contracts* The first meetings of this commission were held in March, 1901, in *The Commission comprised MM. Lorieux, Inspecteur-General (chairman); Re"zal Rabut, Bechmann, ConsideVe, Harel de la Noe, Ingenieurs-en-Chef, Professeurs a 1'Ecole des Fonts et Chausse*es; Boitel, Royel Engineer Officer; Hartman, Artillery Officer; Gautier and Hermant, Architects; Mesnager, Engineer; Candlot, Coignet and Hennebique, specialist contractors. I [271 REINFORCED CONCRETE order to determine the programe of the research work to be carried out. This research work was ordered to comprise enquiries as to the mechanical behaviour of mortar and concrete, with or without reinforcements, more particularly as to the laws of compressive, tensile, shearing, slipping and adhesive stresses, the variations of volume resulting from the hardening pro- cess and from climatic changes ; further, the influence of the proportion and of the qualities of ingredients, the relative efficiency of various arrange- ments for reinforcements, the degree of water-tightness, fire resistance and wear, the effect of shocks and any reciprocal assistance received from neighboring pieces, etc. Further, certain tests "to destruction" were ordered upon various structures in reinforced concrete that had been erected in 1901 for the Paris International Exhibition. Five years were not too much for such experimental research work and for deducing therefrom accurate data, and numerous meetings were held to formulate the results obtained. The conclusions of the "Commission du Ciment Arme" were finally submitted to the Ministry in March, 1906, which department then referred the matter to the approbation of the Conseil General des Fonts et Chaussees, which selected three of its membersf with the examination of the proposed rules. This Conseil thoroughly enquired into every point; called upon the leading members of the "Commission du Ciment Arme" to personally argue their case, and hearing with deference the arguments of the Com- mission's minority,* who had so strongly advocated a separation between the Instructions, i. e. ? Rules, and the Circulaire. The actual reason why the Rules are officially termed "Instructions" is we believe, due to their being considered provisional. We present the "Instructions" (Rules) in full translation and also the explanatory "Circular," which affords such interesting reading. As to the "Instructions" we would, however, indicate certain features in summary as follows : The limit of the safe stresses allowed in designing structures in reinforced concrete Compression. Two sevenths of the crushing strength of the same concrete experimented without reinforcements on a cube after 90 days, hardening. This rate of two-sevenths may be increased to three-fifths if the longitudinal and transverse reinforcements are complying with certain conditions. Shearing, slipping and adhesion. One-thirty-fifth of the crushing strength above referred to for plain concrete. Tensile and compressive reinforcements. One-half of the apparent limit of elasticity to be specified in the device of contraction and five-twelfths only if shocks may occur. tMaivrice L,e"vy, Inspecteur-General, iere Classe, Membre de 1'Institut; de Preaudeau, Vetillard, Inspecteurs-Generaux de 2eme Classe. * Which comprised MM. Rabut and Mesnager: 128] : FREXCH RULES OX REINFORCED COXCRETE All these safe stresses are to be decreased^ but from 25 per cent, at most, when whatever weakening cause may be forseen. Empirical formulae will not be allowed, but only scientific ones. The tensile strength of concrete is to be considered in order to determine the general deformation; but for computing the local stresses it will be con- sidered as nil. The "Circulaire" explains that the ration m of the moduli of elasticity of steel and of concrete was found experimentally equal to 10 by Messrs. Rabut and Mesnager, but that this figure would not be justified indifferently in all cases; this value may vary from 8 to 15 to be inserted in the formulae derived from the elastic theory, according to the diameter of the longitudinal reinforcements and the spacing of the transverse reinforce- ments in ratio of the least dimension of the piece. For pieces subjected to direct compression another coefficient m is to be considered besides the coefficient m amplifying the volume of the longitud- inal reinforcements, and permitting this letter to be summed up with the volume of concrete in order to compute the total sectional area of a fictive homogeneous section equalling, from a mechanical aspect, the heterogen- eous sectional areas. This coefficient m' allows the amplification of the total sectional area (fictitiously homogeneous), according to the ratio of the volume of transverse reinforcements to the volume of concrete and their more or less spacing. The tenour of these rules is to induce the builders to use, as far as pos- sible, large sections of ribs, small .diameters of reinforcements, and close- spaced stirrups. COPYRIGHT. PROPOSED INSTRUCTIONS (Rules) FOR DESIGN OF STRUCTURES REINFORCED CONCRETE. /. Data to be Allowed i?i Designing. to be designed with regard to the maximum A. Loads loads which such structures may have to 1. Bridges in reinforced concrete are to carry. be designed in accordance with the same B. Safe Working Stresses. vertical loads and the same wind pressures 4- The limit of compressive stress for as those required by the Ministerial regu- reinforced concrete to be allowed in calcu- lations of August 29th, 1891, dealing with lations shall not exceed ^ /^ of the crushing steel girder bridges of similar types. strength of plain concrete of the same pro- 2. Roofs in reinforced concrete shall be portions and at the age of 90 days. The treated from the point of view of loads value of the crushing strength, determined as far as possible in accordance with the by tests upon 8-in. cubes at least, to be French Ministerial regulations of February specified in every contract. 1 7th, 1903, dealing with metallic halls for 5. When hooping, transverse, or oblique railway lines. reinforcement is employed, if arranged 3. Floors and other structural features suitably to resist the buckling effect due of buildings, retaining walls, tanks, water to longitudinal pressure, the safe limit mains under pressure and any construction referred to in Article 4 may be increased whatsoever affecting the public safety, are to some extent in proportion to the volume [29] REINFORCED CONCRETE of reinforcing bars, and to their more or less suitable arrangement; but, whatever may be the percentage of the reinforcement employed, the limit of compressive strength shall not exceed 3 / 5 of the crushing strength of plain concrete as stated in Article 4. 6. The safe limit for shearing and slip- ping strains in the concrete in respect of its own fibres, as well as the safe limit of its adhesion to the metal used as reinforce- ment, may be taken as equal to Y of the strength specified in Article 4 for the safe limit of compressive stresses. 7. The safe limit of tensile as well as compressive stresses allowed for the rein- forcement shall not exceed one-half the value of the elastic limit of the metal em- ployed, and as specified in the contract. However, for members, and especially for slabs subject to alternating shocks or stresses, this limit is to be reduced to 5 /i 2 instead of one-half the elastic limit. 8. For members subject to stresses vary- ing within wide limits, the safe working stresses specified above are to be reduced in accordance with the importance of such variations, but this decrease need not exceed 25 per cent. The safe limits of the working stresses are to be reduced also for members subject to weakening causes not considered in the calculations, particularly to dynamical action, and especially for members directly supporting railway lines. //. Calculations. 9. The designer of structures in rein- forced concrete has to take into account not only the most unfavourable external forces, including the weight of wind and snow, but also the strains resulting from changes of temperature and those due to the expansion and contraction of the concrete when the structure cannot be considered, with some certitude, as being freely dilatable, theoreti- cally or practically. 10. Calculations are to be based upon scientific methods derived from experi- mental researches, and not upon empirical formulae; the calculations may be deduced either from the principles of the elastic theory or from principles presenting at least an equivalent guarantee of exactitude. 11. The tensile strength of the concrete shall be taken into account when calculating [30] deformation, but when computing the local stresses in any section, the tensile strength of the material is to be considered as nil. 12. When a member subjected to direct compression is free over a length exceeding 18 diameters (or the least side), it is neces- sary to inquire whether it is liable to flexure. ///. Construction of Works. 13. The moulds and centerings, as well as the disposition of the reinforcement, must afford sufficient rigidity for with- standing, without noticeable deflection, the loads and shocks occurring during construc- tion, including those caused by the removal of moulds and centerings. 14. Except in special cases where con- crete is poured, the cement used shall be slow-setting, and the concrete carefully tamped in successive layers, whose depth shall be suited to the dimensions of the aggregate and to the spacing of the rein- forcement; this depth shall not exceed 2 in. after tamping, except in cases where stones are employed as aggregate. 15. The reinforcing bars are to be so spaced one from the other and from the sides of the moulds, that perfect ramming of the concrete may be facilitated, and that the concrete may be forced into contact with the reinforcement. The thickness of concrete intended to protect the reinforce- ment against changes of temperature must be at least 3 / 4 in., even in cases where cement mortar is used in place of concrete. 16. When special sections are employed for reinforcement instead of round bars, arrangements must be made to provide for the perfect encasing of the bars around their entire perimeter and particularly at all re-interring angles. 17. When the construction of a work has been stopped (an occurrence that shall be avoided as far as possible), the concrete is to be cleaned, scraped and watered for a sufficient time to moisten it thoroughly, before fresh concrete is deposited. 18. In frosty weather the work must be discontinued if efficacious means for pre- venting the prejudicial effects of frost are not available. In resuming the work, any part of the concrete which may have been injured is to be cut out. In other respects, work is to be conducted in accordance with Article 17. FRENCH RULES OX REIXFORCED CONCRETE 19. During 15 days, at least, the concrete must be kept sufficiently moist to insure its setting under favourable conditions. The quality and proportions of the in- gredients of the concrete are to be specified in the contract. The amount of water used in gauging shall be supervised accurately, and must be sufficient for insuring the fluidity necessary for the perfect embedding of the reinforcement and the complete fill- ing of all voids between the various ingredients of the mixture. 20. The moulds and centerings are to be removed without any shock ; the stresses developed in removing them must be merely static and the set of the concrete ought to be sufficient for withstanding such stresses. IV. Tests of the Works. 21. Structures in reinforced concrete affecting the public security must be tested before use. The conditions of testing, as well as the limit of deflection allowed, are to be stated in the general specifications. The age of the works tested shall be specified also, it must attain at least 90 days for structures of primary importance, 45 days for ordinary constructions, and 30 days for floors, 22. The engineers* shall have, in testing, the opportunity not only of observing the deformations and of verifying other speci- fied conditions, but also, as far as possible, of making scientific investigations. 23. Bridges in reinforced concrete are to be tested in accordance with the methods prescribed by the Ministerial regulations of August 29th, 1891, above referred to. Any variations from those regulations that would appear suitable in any particular cases are to be justified and specified in the contract. 24. Roofs shall be tested as prescribed in the Ministerial regulations of February I7th, 1903, above referred to, subject to approved variations. 25. Floors shall be subjected to tests comprising the application of the calculated permanent and moving loads acting over the whole area of the building, or at least upon entire floor panels. The loads are to be left in position for * In this and all subsequent cases where the words the engineers are used they refer to the Ingemeurs des Fonts et Chaussees. En at least 24 hours, and increase of deflection must cease after 15 hours. Proposed Circular Explaining the In- structions for Design of Structures in Reinforced Concrete. Tn consideration of the extensive develop- ment evidenced in reinforced concrete con- struction as applied to public works, it is necessary to call the attention of the engi- neersf to the general conditions under which buildings erected in this new material present the same features of stability and offer the same guarantees of safety to the public as those carried out in materials that have been in use for a long time. Such is the scope of these Instructions. While complying with the actual state of our knowledge on the matter, they may probably be modified when the experience derived from works executed or from laboratory experiments and from the longer use of reinforced concrete shall have fur- nished more accurate data than those avail- able at the present moment. The object of the following explanations is to define more accurately, so far as appears necessary, the meaning and scope of the Instructions. /. Data to be Allowed for Designing. A. Loads. Articles i, 2 and 3. The two first articles require no comment. The third, prescrib- ing that the structures dealt with are to be designed for the most unfavourable loads that they may have to bear when in use, appears unnecessary, as every work must be carried out and thus designed in view of the purpose for which it is destined. That is true for metallic structures or any other class of building construction em- ployed before the introduction of reinforced concrete. Such buildings are designed in view of supporting with a suitable factor of safety the greatest actual loads to be fore- seen, that is to say, so that under the in- fluence of these loads the elastic stress shall not exceed a determined ratio of the loads capable of producing rupture. Some specialists have suggested another mode of procedure for the design of structures in reinforced concrete. Instead t Inge"nieurs des Fonts et Chaussees. [31] REINFORCED CONCRETE of deducing the elastic stresses from the actual loads, their method involves inquiry into the proportion by which these loads would have to be fictitiously increased to cause rupture, this ratio of amplification determining the factor of safety. This method of proceeding, while some- times interesting, evidently does not afford a sufficient guarantee of safety, for the sinking of a building is never caused by a proportional amplification of the loads it has to support. The collapse of a structure is rather the consequence either of an acci- dental occurrence or of an internal injury whose development becomes destructive. Under such conditions it appears proper to design structures in reinforced concrete, as in the case of other constructions, for the most unfavourable loads they may have to support and with such a factor of safety as to give an adequate assurance of stability. Although the first method is obligatory, the engineers may supplement it, if they think proper, calculations based on the amplification of real loads in order to ascertain the hypothetical loads capable of causing rupture, and they may state the conclusions they deduce from these calcula- tions. B. Safe Working Stresses. 4. The value of the safe working stress in compression of the concrete without reinforcement, limited to 2 / 7 of its crushing strength after 90 days hardening, is far higher than the value generally allowed abroad. The figures found in foreign rules correspond rather to an allowance */ 4 of the crushing strength of plain concrete of equivalent proportions after 28 days setting. Making comparison between the two rules for three mixtures of reinforced con- crete examined by the Commission du Ciment Arme, the following results are found: The mixtures tested by the Commission were composed of 400 litres sand and 800 litres gravel and respectively: 300 kilo- grammes; 350 kilogrammes; 400 kilo- grammes Portland cement. The ultimate compressive strength found for these concretes expressed in kilo- grammes per square centimetre were as fol- lows : [32] After 28 days. 107 kilogrammes, 120 kilogrammes. 133 kilogrammes (a) After 90 days. 160 kilogrammes, 180 kilogrammes, 200 kilogrammes (fr) Assuming the limit of the safe stress be a / 4 of the ultimate strength (a), we have re- spectively : 27 kilogrammes, 30 kilogrammes and 33 kilogrammes per cm 2 . Admitting on the contrary 2 / 7 of the strength (fe) according to Article 4 of Instructions, we have : 45.7 kilogrammes, 51.4 kilogrammes, and 5.71 kilogrammes per cm 2 , or almost double the previous values, Therefore, from this standpoint, Article 4 appears far bolder than the foreign rules. But these latter being relatively old, may soon be revised and probably modified so as to come into line with the provisions of Article 4. As French designers comply more wil- lingly that foreign engineers with adminis- trative regulations even for private works, the boldness of Article 4 will be favourable to the development of the reinforced con- crete industry. In any event, designers remain liable for the data they apply. Otherwise the engineers are not obliged to adopt the ultimate limit of the allow- ance; they can prescribe lower limits and should remember that whatever stress limits may be adopted, the stability of structures in reinforced concrete depends very largely upon the perfect quality of the ingredients, their mathematical admixture, and their accurate application. Supervision is to be still more rigorous for such struc- tures than for those in ordinary materials. 5. The intelligent use of the metal, not only for longitudinal but also for the trans- verse and oblique reinforcements, is to be encouraged, in order that it may be able to assist the concrete to withstand the buckling action due to longitudinal pressures. Un- der these conditions crushing strength increases very largely, and when the trans- verse reinforcement constitutes hooping of sufficiently close spacing this increase is considerable, as experiments have shown. Therefore, a higher allowance for the safe working stress seems logical, and this increase is to be determined by the volume FREXCH RULES OX REINFORCED CONCRETE and the suitable arrangement of the trans- verse reinforcement. It would be difficult to ascertain the laws governing this increased resistance. Some tests made in laboratories, or carried out in works, in prisms of concrete without reinforcements and with suitable transverse reinforcement, suggest the rate of increase of the crushing strength of the latter, and, therefore, the corresponding amplification of the safe working stress to be allowed. Neverthe- less, according to the experiments made by the Commission du Ciment Arme, it must be admitted, faute de mieux, that the trans- verse reinforcement and the hooping mul- tiply the crushing strength of a prism of concrete by a coefficient : , V' i+m v V being the volume of the tranverse or oblique reinforcement and V the volume of concrete corresponding to the same length of prism; m' is a coefficient vary- ing with the degree of efficiency of the bond provided between the longitudinal bars. This bond being realised by trans- verse ties constituting rectangles, if pro- jected on a cross section of the prism, the coefficient m' may vary from 8 to 15, the mini inn m relating to a spacing of the trans- verse reinforcements equal to the least dimension of the specimen considered, and the maximum corresponding to a spacing equal at least to the third part of that dimension. When the transverse reinforcement is compounded of more or less close windings, in' may vary from 15 to 32, the minimum being applied to windings spaced 2 / 3 of the least transverse dimension of the specimen considered, and the maximum, if this spac- ing reaches Y S of the above dimension for a longitudinal pressure of 50 kilogrammes per square centimetre, or a / s of the above dimension for a longitudinal pressure of ico kilogrammes per square centimetre. But in any case, whatever may be the percentage of such reinforcement and the ,V value of the coefficient i+m',,-, the former indications have to comply with the essential condition specified in Article 5, viz : that the safe working stress to be allowed must not exceed 8 / 3 of the strength of plain concrete, such as are described in Article 4. The effect of this requirement is, in every case, to keep the working stress within such limits as not to exceed one- half of the pressure causing the first sur- face cracks in the reinforced concrete; which, according to the experiments of the Commission du Ciment Arme, may exceed by from 25 to 60 per cent, the pressure causing the crushing of plain concrete. II. Calculations. 9. This article requires no explanation or comment. 10. The scope of this article is to obviate empirical methods of calculations. The principles of the elastic theory allow safer solutions in the case of reinforced concrete as for ordinary structures. It may be ad- mitted within the limits of experimental researches known up to date, that Navier's theory of the plane deformation of the cross section can be applied here also. This latter, coupled with the principle of proportionality between deformation and stress, is sufficient in the case of members subjected to pressure, if every heteroge- neous section is replaced by a hypothetical section having the same mass as the real heterogeneous section, and if a density i is imputed to the concrete features and a cer- tain density in* to the longitudinal rein- forcements. Theoretically, the density m would be the ratio : Es EC" <'> of the modulus of elasticity Es of the rein- forcement to the modulus of elasticity of concrete EC. The value of this ratio is about 10 within the limits of loads assumed in Article 4. It increases with the loads of concrete, and may double or triple when rupture occurs by crushing ; it will decrease, on the contrary, in case of rupture caused by failure of the reinforcement. This fact would suffice to show the incer- titude of calculations based on a fictitious increase of loads up to rupture, as stated in Article 3. In all cases the experiments in view of * The transverse reinforcement has nothing to do here. Its essential effect is already taken in con- sideration in permitting increase of (Article 5) the safe limit of the compression of concrete. In fact the lead- ing efficiency of the transverse reinforcement is to increase the crushing strength of concrete by with- standing the transverse buckling. [33] UNIVERSITY OF CAUFORHIA REINFORCED CONCRETE the determination of EC were made with plain concrete. To what extent the ratio m deduced from those experiments may be applied to reinforced concrete? That de- pends, probably, on the degree of facility with which the members may be rammed in all their parts for a complete embedding of the reinforcement. Therefore, it is preferable to consider the coefficient m as resulting from tests and not necessarily as representing, in a member with complex longitudinal and tranverse reinforcement, the ratio of the elastic mod- uli of the metal and of the concrete tested separately. It will be assumed that this coefficient may vary from 8 to 15. The minimum is to apply to diameters of longitudinal bars equal to l / w the least dimension of the mem- ber, the ties or tranverse reinforcement being spaced apart, this latter dimension, and having their ends sufficiently near the surface of the concrete. The maximum is to be applied in the case of diameters of bars equal to V 2 o of the least dimension of the member, and their spacing reduced to 1 /s of this dimension. Most authors admit a constant value for m and often take w=i5. By so doing, they may ascribe in many cases too much strength to the metal and too little to the concrete in relation to the stresses really occurring. In consequence of this assump- tion, the working stress of concrete may be, in fact, higher, and the factor of safety lower than is presumed. Letting m vary from 15 as maximum to 8 as minimum according to the disposition of the reinforcement, longitudinal and tran- verse as well, the truth is approached more nearly, and compensation is found for the rather high working stress allowed in Arti- cle 4. Once the coefficient m has been decided, it is easy to apply formulae under the class- ical form dealing with homogeneous bodies. (a) Simple compression. The hypotheti- cal homogeneous sectional area ft is given by the relation: ft = ft+-; W ft (2), ftc, being the sectional area of concrete and fts the total area of the cross sections of the longitudinal reinforcement. The latter being very little in proportion to the [34] first, it should be noted that we may con- sider the total area ftc + fts instead of ftc of the member. Let N be the total pressure acting nor- mally to the section, Re the pressure per unit area borne by the concrete, and Rs the compression supported by the reinforce- ment, we get : _N N "ft' - w ft (3). Re being assigned, ft is deduced and then, by means of formula (2), according to the actual shape of the member, the total area fts of the reinforcement or the percentage: a ftc' (fe) Compression with flexure. If the total compression N is not uniformly dis- tributed, besides the area ft of the hypothet- ical section, resort must be had to the centre of gravity of the section and to its moment of inertia about the perpendicular to the di- rection of flexure drawn through the center of gravity, according to the following equa- tions : fly =. ftjj/,. -+- wiQy R (4), I L+mL (5). Fig. i is a diagram of the section con- sidered, assumed to be symmetrical about the axis y'y. The centre of gravity of the hypothetical section ft to be ascertained is G ; that of the reinforcement Gs is known ; that of concrete Gc is also known. These points are determined by their respective ordinates : starting from the axis x'x, arbitrarily chosen, and expressed conventionally with the + sign when on one side, and with sign when on the opposite side. Equation (2) gives ft; FRENCH RULES ON REINFORCED CONCRETE then equation (4) gives the ordinate of the centre of gravity G of fi ; next, the axis xGx' being known, the moments of inertia Ic and Is of the geometrical areas of con- crete, and logitudinal reinforcement can be computed about that axis, and finally, equa- tion (5) gives the moment of inertia I of the hypothetical section fi, about the same axis. It was said above that the total section fit = fl e + fi, of the member is sometimes taken instead of the section fie of concrete. If not so taken, equations (2), (4) and (5) may be written more handily in practice by inserting the total area instead of fie, the area of concrete. Then, inserting instead of the centre of gravity G c of concrete (that G t ), of the total section, and instead of the moment of iner- tia, I c of the sectional area of concrete about the axis x'x the moment of inertia It of the total Section about an axis parallel to x'x passing through the centre of gravity Ct. The formulae then become: fi = fi + ( m i) fi y> fly = fly t + (m I) fly,, Then, N being the total pressure and M the bending moment, or the sum of the mo- ments of external forces acting on the section considered about the centre of gravity G of the hypothetical section, the unit pressure n c acting on the concrete at any distance v from the axis x'x will be: and if at the point considered there is a bar of reinforcement, its corresponding stress would be : In these formulae, the distance v is to be considered as positive on the side where the bending moment causes compression, and as negative on the opposite side. If the bending moment about the axis x'x is considered positive from left to right for an observer placed on x'x, the head in x', the feet in x, then the distances v are to be considered positive for the points of the section located at the right of x'x and nega- tively for those laying at left. Let us call v c the distance from x'x of the extreme fibres at the right hand, Vi c the absolute value of the same distance for the extreme fibres at the left hand, the maxi- mum compression of concrete R c per unit of area will be: The minimum compression R ie will be: R, = *--%. .(7). Replacing the suffix c by ^ for the rein- forcements, the maximum values of com- pression for the reinforcements will be: (8'). These formulas assume essentially that there is compression at all points, or, in other words, that the value Ri c and there- fore the value Ri s are positive. If R Js were negative they could not be applied, because the laws of extension of concrete differ essentially from those governing its com- pression. The proper process will be indi- cated hereafter. If we know the total pressure N in amount and direction, that is, if we know the position of its point of application (cen- tre of pressure) determined by its co-ordin- ate v about the axis x'x, it can |pe deduced by definition that M = Nv . (9) Thenwriting: I = fir 2 (10) r being the radius of gyration of the hypo- thetical section about the axis x'x, we should get: N The neutral axis would be obtained by expressing the value n = o, or: O (12) if we call v the value of v, determining the position of tnife-'axis. With these 'new notations, equation (7) becomes: XT / _. -. \ (13) Comparison of the two last formulae shows, as it ought, that there is compres- [35] REINFORCED CONCRETE sion at all points only when the neutral axis falls outside the section, or: V > Vic. The above consideration supposes that the values of N and M are known for every section. Such will be the case for a column bearing a central load that is applied in the centre of gravity of the hypothetical section, where M=o, or eccentric, where (M = Nv ). It will similarly be the case in a dam for which the line of pressures gives in fact N and v for every section. When these values are not given directly by static methods, as in the arch of a bridge, it is necessary to proceed as in the far most general case of members at once compressed and extended, a case which really justifies the use of reinforcement, and we enter nat- urally upon the treatment of the case dealt with by Articles n and 12 of the Instruc- tions. It was stated in that Article, that in cal- culations dealing with deformation, the ten- sile strength of concrete is to be taken into account. These calculations are necessary when the deformation is to be determined, particularly to estimate the deflection taken by the work. But in every case these for- mulae of deformation are to be applied for computing in all sections the pressure N of the average fibre (geometrical locus of the centres of gravity G of the hypothetical sections 0), the bending moment M, and the shearing stress T, when they cannot be determined by static methods. By definition, N and T are the normal and tangential components of the external forces, including the reaction of the support acting on a determined side of the section, and M is the sum of the moments of the same external forces about the point G. In the case of a column with one end free, or of a beam simply supported at the ends, the forces N and T and the couple M can be accurately computed. Hence no formula of deformation, and therefore no assumption, are required in order to determine them. Article n does not deal with this part of the subject. But in the case of built in or continuous beams, extending over several supports, or of arches subject to tensile stresses, the .general rule for arches of reinforced con- '[36] crete (Article n) is to be applied, and consequently wants to be interpreted. The engineers may accept the usual inter- pretation although inaccurate, while assum- ing for concrete subjected to tension the same coefficient of elasticity as when sub- mitted to compression. This assumption once made, the foregoing formulae may be applied in their entirety, under the essential restriction that compres- sive stresses only are dealt with. Now it is easy to see that these formulae, owing to the intervention of the features of the hypothetical section tt, permit us to sub- stitute for the problem of resistance of a reinforced concrete member that is of a heterogeneous member by a problem of resistance of a hypothetically homogeneous member. Then all the general and classi- cal results deduced in respect of the latter case may be applied to the former, and in consequence, in order to compute the values of N, M and T for an arch, and the values of M and T in the case of a beam trans- versely loaded where N=o, as the reac- tions over the supports it will suffice in every case to insert the well-known values referring to homogeneous members. So, if we have a reinforced concrete beam with a span /, built in at both ends and sup- porting a uniformly distributed load of p kilogrammes per lineal unit, it will be ad- mitted as for an homogeneous beam, that the maximum bending moment developed at the ends will be , and that the bending moment at the centre will be of opposite sign and equal in absolute value to . For a beam with the ends partially built in p p the intermediate value may be adopted between and ~ for a beam free on both 24 supports. In the same way, for a continuous beam extending over several supports generally equidistant the values given by treatises on the strength of materials for bending mo- ments, shearing forces and reactions of the supports, for homogeneous members, may be applied, or in special cases, may be deter- mined directly in the same manner as for homogeneous members. In llic same way, for the design of arches FRENCH RULES ON REINFORCED CONCRETE the tables of M. Bresse relative to homo- geneous arches may be used to compute the thrust of a two-hinged arch, and the tables lately published by M. Pigeaud in the Annales des Fonts et Chaussees, on the case of an arch built in, and intermediate values may be adopted between those given by these tables if the building in is thought to be only partial. In special cases the thrust will be directly computed by the classical formula for homogeneous members. The thrust and the vertical reaction once known, all the necessary data will be at hand to determine M, N and T graphically or mathematically for any desired section. More Accurate Interpretation, The ten- sile strength of concrete may be taken in account more accurately if we admit as re- sulting from various experiments the fol- lowing principle : the modulus of elasticity of reinforced concrete, subjected to tension, may be considered nearly constant until the ultimate tensile strength of the same con- crete without reinforcements is reached; the material becomes to some extent plastic, that is, it is lengthened in consequence of its connection with the reinforcement, but without any alteration of its ultimate strength in tension. There is no difficulty in setting up a theory of the resistance of materials based on this hypothesis, coupled with the assumption of Navier concerning the plane deformation of cross-sections. But the calculations become far more com- plicated. However, the engineers may re- commend this method if they find it more suitable. Whatever may be the method adopted for the determination of the values of the bending moment M, of the shearing force T, and of the pressure of the average fibre (which is zero in the straight beams tran- versely loaded), the local stress is to be deduced, at any rate for the most heavily loaded sections. Article n prescribes that the tensile strength of concrete is not to be considered for that object. This require- ment is not at all contradictory with the prescription that it should be taken into account for the calculation of deformation. Tn fact, the cracks of the concrete are more or less of importance near the reinforce- ment in tension, but the alteration of the general deformation of the structure caused by these hair surface cracks is scarcely ap- preciable, even if, at a point, a more appar- ent crack is produced. But at any such point the local stress would obviously be extensively increased. It is, therefore, pro- per to admit this favourable hypothesis in the calculation of local stresses, while it would be improper to admit them in the in- vestigating of general deformation, and consequently for the computation of the values of M, T, N depending upon them. Application to a Slab in Combination with a Rectangular Beam. We will now apply the method stated above to a slab (Fig. 2) , assimilated to a T beam, the height of which is h, the breadth of the flanges is b, the breadth of the rib is b', the depth of the slab is e, and the total sectional area of the reinforcement in com- pression is w, its average distance from the compression face is d; the sectional area of the reinforcement in tension is a/, its dis- tance to the tension face is d '. If the for- mer reinforcement does not exist, w=o. Let y be the unknown distance of the neutral axis xx from the compressed face B. In Fig. 3 the section of the slab is pro- jected about the straight line AB. The ordinates of the straight line XB' represent the pressures of concrete, and if m is neglected the ordinate bb' represents the pressure of the compressive reinforcement, and aa' represents the stress of the tensile reinforcement. Let K be the angular co- efficient or trigonometrical tangent of the angle B'xB. (a) Simple Flexure. In case of simple flexure N=o. Assuming that the elastic forces are limited to the couple of flexure M, that is, their sum =O and the sum of their moments about any point for instance, about the point B is equal to M; then the distance XB=yi of the neutral axis from the compressed face is given by the quad- ratic equation: [37] REINFORCED CONCRETE = i }+mu(yid) m R's, the difference w'(R"s R's\ will tend to produce the slipping in its encasing of concrete of the portion A s of the reinforcement. There- fore, if the total perimeter of the tensile reinforcements is x', the adhesive strength per unit of area will be: The value of this ratio is not to exceed for the safe adhesive stress prescribed by Article 6. If stirrups or other transverse reinforce- ments are sufficiently connected with longi- tudinal reinforcement so as to prevent any slipping of these latter in casing of concrete, then the shearing stress in the transverse reinforcements along A s, or the product of the total sectional area which is in shear by the safe working stress allowed for the metal, is to be deducted from the stress '(R"s R's), and it suffices that the ratio: co'R'.-R'Q-F *'A S does not exceed the safe adhesive working stress. But mere ties connecting the transverse with the longitudinal reinforcement are not sufficient for resisting the force F. These ties are necessary, but their assistance to the adhesion is not to be considered. Longitudinal Slipping of Concrete in itself and Shearing Stress. Let us con- ceive a portion of the member limited by the two cross-sections AB and A'B' (Fig. 5), spaced A s apart, and including the long- itudinal tensile reinforcement a'b'; mn is a cross-section made in the tension area of the concrete, that is, between the reinforce- ment a'b' and the plane of neutral fibres. Let w, ; =:area of that section. As the tensile stresses of the concrete normally to mB and nB' are not taken into account, the portion mnBB' is balanced by the influence of tensile stresses w' R"s and w' R's of the reinforcement and of the longi- tudinal stress, or shearing stress, along mn. Therefore, this stress per unit of area ".- R',) (a), must not exceed the safe limit allowed for shear. If transverse reinforcement efficiently re- [40] sists the longitudinal slipping, it is allowed to take it into account, as stated above, for adhesion. This stress (a) remaining constant as far as the neutral axis, and decreasing further owing to the effect of pressure, the amount above considered is a maximum. The amount of the shearing force at any point is otherwise equal to the longitudinal slipping above referred to. 12. Comparison with Flexure. Euler's formula, applied with a suitable coefficient, permits the design of a compres- sion member without flexure. It permits computations of the'safe load N not to be exceeded, that may be borne by a member of the length = I, hypotheti- cal section = fi, minimum radius of gyra- tion = r, relative to the various axes passing through the centre of gravity (for symmet- rical members the radii of gyration about the bending axis or normal to the plane of symmetry are generally to be considered). The expression of N is: < U EC is the modulus of elasticity of concrete (its average value being one-tenth of the modulus of elasticity of steel), t is a factor of safety and K a coefficient depending on the manner in which the ends of the mem- ber are fixed, and having the following values : Methods of fix- ing the ends. One end fixed and the other free . . Both ends rounded One end fixed and the other rounded Both ends fixed . \ K Observations. If the fixing is im- perfect, an aver- age value is to be taken between YL and i. If one of the fix- ings is imper- fect, an average value is to be taken between^ and Y* ; if both are imperfect, between kand i. As regards the factor of safety, the re- sults obtained will be comparable with those FREXCH RULES OX REINFORCED CONCRETE given by Rankine's formula for great lengths in admitting: y = IOOOR., Re being the safe compressive working stress allowed by Articles (4) and (5) of the Instructions. We then shall have : i ooo Re w-fir 2 -ir or approximately: loooR, OH ~ ' III. Part iy. The Instructions concerning the practical construction of works and tests repuire neither comment nor explanation. It will be remembered that the reliability of works in reinforced concrete is largely based upon their perfect construction. The accidents which have occurred in the past have been due, as a rule, to bad selection or preparation of materials. Specially stringent supervising is, therefore, to be ex- ercised on the nature and clearness of the materials, on their mixture, the amount of water employed, the ramming and forcing the concrete along and around the rein- forcement, and the correct disposition of these latter, etc. As for tests, they may be simplified in some cases if justified; but it would not be proper to endeavor to save money or trouble if these advantages involve the least risk to the public. [41] REINFORCED CONCRETE CONSTRUCTION Its advantages as a structural material for factories , together with a description of re- inforcing systems By Walter Mueller ABOUT forty years ago a French gardener, Joseph Monier by name, devised and patented a method of reinforcing concrete, successfully applying it in the construction of flower pots. From this small beginning an industry has been developed which has revolutionized building construction, and in the opinion of authorities, it marked the inception of the greatest advancement made in building con- struction since the introduction of structural steel. Reinforced concrete is a technical name for a method of fireproof con- struction in which the only materials used are cement, sand, broken stone and steel. Concrete is a combination in proper proportions of the first three, forming a hard and permanent substance similar in texture and hardness to granite. Any good building material must resist the pressure and pull of weights and stresses. The concrete resists the pressure and the steel the pull. The proper combination of these two gives any structure capacity to carry weights. Steel is added to the concrete to produce elasticity, which is essential to any good building material. This addition of steel is called rein- forcement hence the name reinforced concrete. Although the application of reinforced concrete was at first and is still mainly confined to beams and floor slabs, entire buildings are now erected of it, comprising factories, office buildings, hotels, apartment houses, churches, public buildings, grain and cement bins, smoke stacks, etc. In engineering construction it has been used for bridges, sewers, walls, dams, tanks, etc. In fact, its field appears to be almost unlimited. To the manufacturer reinforced concrete construction is of peculiar in- terest, due to the advantages concomitant with its use in the erection of fac- tories, warehouses, etc. The predominating advantages claimed for reinforced concrete con- struction are : (i.) Economy. (2.) Ease and rapidity of erection. (3.) Durability. (4.) Fire-resisting qualities. (5.) Impermeability to moisture. (6.) Even- ness of temperature and deadening of sound. (7.) Monolithic nature of reinforced concrete structures. [42] REIXFORCED CONCRETE CONSTRUCTION THE LARGEST REINFORCED CONCRETE WAREHOUSE IN THE UNITED STATES. BUILT FOR FARWELL, OZMUN, KIRK & COMPANY, ST. PAUL, MINN., AND REINFORCED THROUGHOUT WITH THE KAHN TRUSSED BAR REINFORCED CONCRETE WAREHOUSE FOR THE OLIVER CHILLED PLOW WORKS, SOUTH BEND, INDIANA. KAHN TRUSSED BAR USED AS REINFORCEMENT [43] REINFORCED CONCRETE Economy The main item making for economy in reinforced concrete construction is the unskilled labor which is employed in connection with it to so large an extent. How large a factor this is and how its importance is being realized has lately been shown in two leading instances. The Greater New York Executive Counsel of the Bricklayers' Union has recently adopted regulations to the effect that whenever and wherever concrete is used in building construction within the limits of Greater New York the work must be done by union bricklayers, none of whom will here- after seek or accept employment from any contractor, owner or architect failing to comply with this requirement. Moreover, the bricklayers will insist not only on laying concrete blocks and making concrete floor arches but also on the right to dump the concrete into forms, which has heretofore been done by laborers, at the regular bricklayers' wages of seventy cents an hour. The work of laying concrete blocks is regarded as bricklayers' work now. In regard to the laying of concrete blocks no objection can be made by any fair minded man regarding the justice of this particular demand. But when it comes to paying bricklayers' wages for dumping concrete into forms a horse of another color enters the arena and there is bound to be a clash between the union and the builders. The outcome of this struggle will be awaited with much interest. In the reconstruction of San Francisco it is planned to use reinforced concrete to a large extent but the action of the labor unions in laying all sorts of obstacles in its way will undoubtedly be a considerable deterrent. Due to the powerful political influence wielded by the labor unions in San Francisco they are directly in control of the building situation, ?nd reports indicate that reinforced concrete construction the only form of construction adapted to successfully withstand seismic disturbances and the, in most cases, subsequent conflagrations, is receiving unmerited opposition. Another source of economy in reinforced concrete construction lies in the comparative lightness of structures erected according to this method, thus affecting a considerable saving, in very many instances, in foundation work. The thinness of the walls, floors, etc., more than compensates for the extra cost of the concrete required in the mixing and depositing of con- crete and in the placing of the reinforcement. A seven or eight-inch rein- forced concrete wall will replace one of brick twenty-five inches thick. This would amount to an increase in available renting space in an office building 1 of about 15% and a proportionable earning in the investment. Objections are sometimes raised against the large amount of false work needed for forms. As this false work, however, is usually of a very simple nature it requires no special treatment and very few timbers of large size. In addition, the amount of false work is largely reduced by the fact that many parts of the building can be molded on the ground before erec- [44] REINFORCED CONCRETE CONSTRUCTION THE CLINTON REINFORCING SYSTEM, SHOWING THE METHODS OF USING THE FABRIC ON THii FLOORS OF THE HARBOR SHEDS AT MONTREAL 3&&*tt?ttXtt*&^tt&& ; &ZteK&*tttt*&&&JS^&tt*ti ---i DIAGRAM OF SYSTEM D, TYPE II, OF THE CLINTON REINFORCING SYSTEM PICTURED AT THE TOP OF THE PAGE, SHOWING THE METHOD OF EMBEDDING THE MESH [451 REINFORCED CONCRETE tion. The comparative lightness of reinforced concrete arches compared to those of masonry and brick work permits the centering to be much lighter than that generally employed. Rapidity of Erection The ease and rapidity with which a reinforced concrete structure can be erected. constitute two of the greatest advantages of this form of construc- tion. Walls can be molded a great deal quicker than they can be built of stones or bricks, and floors and roofs are molded at the same time as their supporting beam's/- -Another point making for rapidity is in that the material employed is easily procured and requires no such treatment as that of dress- ing stone, or the making of girders to dimensions. The iron or steel reinforcement is almost entirely in the form of round rods, hoop iron or wire. The reinforcement is in most cases simply laid in place or perhaps. tied with wire at crossing places and requires only such simple blacksmith work as can be done at a portable forge at the site of the work, or the pieces may be cut to the necessary dimensions before delivery. The Durability of Reinforcements The experience of thousands of years has demonstrated that concrete is absolutely indestructible. That it resists the disintegrating effects of air, moisture, water and steam, and even of sea water and of sulphuric and chlorine gases. Some of the most ancient structures in the world are built of this material and are to-day apparently in as sound a condition as they were at the time they were first completed. In fact, they are sounder be- cause tests have demonstrated that the resistance of concrete increases with time. The cost of maintaining a reinforced concrete structure is almost noth- ing, comparing more favorably in this respect than do structures erected of steel and iron, which require almost as continual supervision as do those erected of brick or stone. As no boring animals can work their way into reinforced concrete struc- tures of this material, therefore, are free from all sorts of vermin. Neither will such structures harbor microbes, due to the freedom of the material from pores. Thus in the matter of hygiene reinforced concrete is the most satisfactory material for the construction of abattoirs, factories, ware- houses etc. The Fireproof Qualities of Concrete The fire resisting qualities of reinforced concrete are perhaps of great- est interest to the manufacturer. There is no doubt but that reinforced concrete is the best material for fireproofing construction since concrete protects the embedded skeleton by reason of its low conductivity of heat. This was shown to be the case in the conflagrations of Baltimore and San [46] REIXFORCED CONCRETE CONSTRUCTION THE FALSE WORK, SHOWING THE PRELIMINARY STEPS IN THE CONSTRUCTION OF A CON- CRETE FLOOR REINFORCED BY THE UNIT SYSTEM PLACING THE UNIT BARS IN POSITION BEFORE THE OPEN SPACES ARE FILLED IN WITH CONCRETE [47] REINFORCED CONCRETE Francisco. As the coefficients of expansion of concrete and steel are equal there is no danger from collapse in a reinforced concrete structure. In the case of terra cotta and steel, a form of construction which is being rapidly supplanted by reinforced concrete, the coefficient of the former is double that of the latter and therefore collapses are bound to occur under high temperatures, due to the largely increased expansion of terra cotta over steel. Impermeability The resistance of reinforced concrete to the penetration of water is another one of its most advantageous properties and gives it a distinct ad- vantage over brick and masonry for aqueducts, reservoirs, tanks, etc. For certain industries where vats and big tubs are used reinforced concrete has proven itself far superior to timber and it has been found to withstand the action of alkalis and acids far better than iron or wood. Equability of Temperature and Soundproof Qualities The poor conducting qualities of concrete keep the rooms erected of it at a very equable temperature. This is a special advantage where they are near the roof as in ordinary buildings, where they are apt to be unbearably hot in summer and excessively cold in winter. The efrect on sound is the reverse by consequence of the wall being thin. And where single walls are employed sounds penetrate in a marked degree. It is a very simple matter to employ double walls in this form of construction as they may be made very thin and united by bonding in cross ties, so that the two walls act as one in resisting stresses. Floors are also made double, the ceiling slab being separated from the floor slab. The same method is also employed in the construction of roofs. . Monolithic Nature and RigMity A structure of reinforced concrete is not, as is sometimes supposed, an assemblage of parts connected together in a more or less thorough manner. It is a unit, each part of which is connected with the neighboring pieces. This intimate connection gives a strength to a structure unknown prior to the introduction of reinforced concrete and also affords an almost perfect resistance to vibrations. This resistance is perhaps most noticeable in buildings containing machinery where the absence of vibration is not only beneficial to the building itself but also to the machinery in it. The latter runs more smoothly and not being subject to external vibration enjoys a longer life. Fast "running machinery such as that used'in the operation of dynamos or centrifugal pumps is especially benefited by being placed in buildings of reinforced concrete. For structures on bad or swampy ground reinforc- ed concrete enjoys a peculiar advantage. A reinforced platform under the building supported, if necessary, on reinforced concrete piles makes an [48] , < -! REIX FORCED CONCRETE CONSTRUCTION REINFORCED CONCRETE WAREHOUSE OF THE STANDARD TABLE OIL CLOTH COMPANY, AT YONKERS, N. Y HENNEBIQUE SYSTEM THIS PICTURE SHOWS THE USE OF CLINTON ELECTRICALLY WELDED FABRIC OX THE REIN- FORCED CONCRETE ROOF OF THE DECAUVILLE GARAGE, NEW YORK [49] REINFORCED CONCRETE ideal foundation and their monolithic nature enables them to resist the stresses of unequal settlement. . In addition, such a building is also lighter than one of regular brick work or masonry which is another advantage. Systems of Reinforcement The astonishing spread of reinforced concrete construction has natural- ly brought about a corresponding development in the methods of reinforc- ing. In the following pages we have endeavored to outline in brief the im- portant features of a number of reinforcing systems which are in extensive use to-day in reinforced concrete work. While steel in small sections is used almost entirely for the reinforce- ment there is a great variety in the shape and character of the metal em- ployed. For the flat systems some form of netting or fabric is most commonly used, while for beams, bars or cables of various sections are employed. In some instances plain round or square bars or wires are used, but practice in this country has demonstrated the importance of the shape of the reinforcement being such that it will offer resistance to slipping in the concrete, independent of the adhesion of the mortar. In this connection Mr. Edwin Thatcher, a prominent civil engineer, states that "although the natural adhesion between concrete and steel appears to be very great, he does not consider it wise to place reliance upon any concrete steel construction, but provides mechanical connection suffi- cient to ensure its safety in case the adhesion from any cause amounts to little or nothing," The Kahn System This system, which is being advocated by the Trussed Concrete Steel Co., of Detroit, Mich., embodies the use of what is known as the Kahn trussed steel bar. This bar is rolled of a diamond section with projecting wings on either side. The wings are slotted off along the edge of the dia- mond for certain distances and are bent up to an angle of about forty-five degrees to form the reinforcements resisting the shearing stresses. They are consequently rigidly connected to the main bottom bars. The three principal advantages claimed for the employment of this form of reinforcement are : 1. The reinforcement in the vertical plane is rigidly attached to the main horizontal member and lies in such a direction as to cross at right angles the lines of rupture. 2. The design of the diagonals economizes in the amount of metal re- quired and enables same to be placed with a maximum amount of speed and economy. 3. Absolute fireproofness of structures is the result because this rein- forcement does not depend upon the lower part of the concrete, which is affected by fire. [50] REINFORCED COXCRETH CONSTRUCTION REINFORCED CONCRETE RESERVOIR IN COURSE OF CONSTRUCTION FOR THE U. S. GOVERN- MENT AT KEY WEST. EXPANDED METAL AND KAHN TRUSSED BARS USED AS REINFORCEMENT FACTORY RCOF BUILT IN ACCORDANCE WITH THE FERROINCLAVE SYSTEM, CORRUGATED METAL WITH CONCRETE ABOVE AND BELOW [51] REINFORCED CONCRETE The warehouse for Farwell, Ozmun, Kirk & Co., at St. Paul, Minn., which is stated to be the largest reinforced concrete warehouse in the United States, was reinforced throughout according to the Kahn system. The entire interior construction, including such structural members as column footings, wall footings, columns, girders, beams and floor slabs is of rein- forced concrete. The building is nine stories in height and the actual floor area is approximately 450,000 square feet. The floors are designed to carry the heaviest hardware warehouse load- ings, which would be equivalent to 500 pounds per square foot over the en- tire area of the floor. Whole panels have been tested up to 1,500 pounds per square foot with- out any appreciable effect on the floor construction. This is a remarkable load and was obtained by piling pig iron as densely as possible to a height of eight feet on one complete panel. Were this load to be placed upon a truck it would require forty horses to haul it away. The pig iron resting on the floor stood two feet higher than the head of a six foot man. It was al- most impossible to get a greater load on the panel as there was almost solid iron from the floor to the ceiling. The Clinton System A reinforcing for concrete construction of all kinds which is being ex- tensively used in this country is the electrically welded fabric manufactured by the Clinton Wire Cloth Company, of Clinton, Mass. The late Frank E. Kidder stated that from a theoretical standpoint at least this fabric would seem to oifer the ideal reinforcement for slab construction, as the carrying wires may be varied both in size and spacing to give the necessary area for any given weight and span. The distributing or cross wires may like- wise be varied in the same way. The direction of the wires coincides with the line of stress so that there is no tendency to distort the rect- angle of the mesh. As this fabric comes in 3oo-foot rolls it can, in a building say, for instance, 200 feet long, be secured at the front or rear and carried through the entire distance without a break. Owing to the continuous bond the reinforcing is equally strong at all points and the reinforcing members are exactly spaced 2, 3 or 4 inches apart as the case may be. This spacing? is exact; it is established by machinery and is not subject to the care- lessness of employees. Due to the continuous bond secured by the Clinton fabric no entire collapse of any arch erected with it can occur, unless the weight imposed on the arch is sufficient to strain and break all of the wires. In the Produce Ex- change National Bank, New York, arches 14 feet 8 inches center to center of beams were put in place and some of them not being protected were al- lowed to freeze. These arches were reinforced with the Clinton fabric. They subsequently thawed out, froze and thawed out again. The result was [5*1 REIXFORCED CONCRETE CONSTRUCTION that although the concrete was rendered worthless and despite the fact that the reinforcement was carrying not only the weight of the damaged con- crete but also the weight of all materials moved through the rooms, work- men, machinery, etc., and was withstanding the rough usage to which buildings at that stage are subjected, each of the arches remained intact due to the continuous bond of high tension steel wire extending throughout the entire width of the arch and securely fastened around the outer flanges of the I-beam. The Unit System In the Unit system, which is controlled by the Unit Concrete Steel Frame Company, of Philadelphia, all of the metallic reinforcement for each beam or girder is made into a single unit and placed as a unit in the form. This is accomplished by having both the straight and camber bars fastened together by stirrups and clamps, so that each tension and shear member is rigidly held in its proper position. This precludes the possibility of one or more members being omitted or incorrectly placed by workmen at the building, and affords opportunity for inspec- tion prior to use. Its exact position in the form is fixed and rigidly secured by means of what is called the Unit socket, made of cast steel of ij or 2 inches in height, as may be required by specifications for fireproofing. This socket is tapped for a f-inch bolt, and is bolted into the bottom of the mold. A f-inch threaded stud projects from the top of the socket. Four or more of these sockets are placed in the mold, usually four or five feet apart, and the girder frame is then set upon them in a manner to permit of the stud protruding between the main bars of the girder frame. The girder frame is then secured and rigidly held by a washer and nut screwed down on this stud over the frame, and inspected as to their accuracy before being covered by the concrete. The sockets are afferward utilized, in many instances, for the support- ing of shafting, motors, piping or other overhead fixtures. Another feature of this system is the punch stirrup, permitting and requiring the lacing of the slab rods through the eyes of 'the stirrup, thus making a metallic connection between the slab and the beam or girder. The advantages claimed for this system are absolute accuracy in the placing of the reinforcing material ; the ease with which it can be inspected and errors, if any, detected and corrected before concreting; the impossibility of omitting any tension or shear member ; the addi- tional strength secured by binding the slab concrete to the beam con- crete by means of lacing of the slab reinforcement through the stirrups, The girder frames may thus be set in advance of the concrete work, and the provision for shafting or other overhead fixtures. [53] REINFORCED CONCRETE The Hinchman-Renton System While plain iron rods have never been known to slide or slip in concrete yet on account of the possibility that the sliding resistance along the em- bedded steel will decrease in time under frequently repeated loads, Amer- ican engineers have deemed it wise to use the reinforcing steel in such shape that sliding in the concrete will be impossible without tearing and crushing. In seeing for material that would satisfactorily supply the tensile strength required by floor slabs it occurred to Mr. J. B. Hinchman of the Hinchman-Renton Company, Denver, Colorado, that ordinary barbed wire would afford the necessary reinforcement. In addition barbed wire is also inexpensive and readily obtained in any quantity. Test slabs were therefore made by the above mentioned company on the Monier principle by using the barbed wire in place of plain rods and wires. These tests proved so satisfactory that the company decided to use barbed wire in their future work and applied and secured patents on its ap- plication in concrete floor construction. Excellent results have been obtain- ed with this method of reinforcement. For concrete beams of long spans a greater sectional area of the material is required than can be obtained with barbed wire. Hence where the span exceeds eight feet the Hinchman-Renton Company has adopted a punched channel bar as the reinforcement member. Owing to the great surface of these channels in proportion to their weight, and the perfect key obtained with the concrete they have been found to possess superior qualities. In addition they are economical and can be readily obtained in any quantity and of various dimensions. By the use of this tension bar, with cross ties of barbed wire, it is practicable to con- struct floors having a clear span of 20 feet and to erect a monolithic concrete structure without the use of steel floor beams. A test slab 41-4 inches thick, 40 inches wide and with a clear span of 6 feet, reinforced according to the system advocated by the Hinchman-Ren- ton Company showed a carrying capacity of 1,300 pounds or 650 pounds a sq. ft. with apparent safety. This slab was formed in a box and was set loose on top of the steel beam. Experience has shown that when built in place, as in actual construction, the carrying capacity is greatly enhanced. A similar slab made at the same time and of exactly the same composi- tion but without the barbed wire, failed without warning under a load of only 28 pounds per square foot, showing that there is perfect adhesion be- tween the concrete and the barbed wire tension members. It is a well known principle of engineering that a continuous slab sup- ported at the four sides will support a much greater load than if divided into separate beams without connection at the sides. Reinforced concrete floors in building have time and again shown a strength that would appear [54] REINFORCED CONCRETE CONSTRUCTION THE CRANDALL TWISTED STEEL BARS, SHOWING THE METHOD OF USING THEM IN REINFORCED CONCRETE CONSTRUCTION WORK incredible if the fact were overlooked that the floor is monolithic over this channel and that the strength radiates in all directions from the points of support. The Hinchman-Renton Co. are prepared to construct and guarantee fireproofing by their system which shall sustain a universally distributed load of 1,000 pounds per square foot and over with a clear span of six feet. The Columbian System This is a flat concrete system with ribbed steel tension members. Rolled joists are used for beams, embedded in concrete, the double cross [551 REINFORCED CONCRETE floor reinforcements being held in place by flat iron inverted stirrups placed over the top flanges of the joists. The vertical ledge of the stirrups are slotted out in the shape of double cross sections and the floor bars are housed in the slotted holes. The bottom flanges and the roof joists are especially protected against fire by troughs of concrete, in the sides of which pieces of hoop iron are im- bedded with their ends projecting. These are clipped around the flange of the joists and hold the joists against the bottom surface. The hollows thus formed leave an air space between the concrete and the under side of the flanges. All reinforcing steel, connected angles and stirrups are made from mild steel of either open hearth or Bessemer process, having an ultimate strength of 60,000 to 70,000 pounds per square inch and an elastic limit of not less than one-half the ultimate strength. All material is care- fully tested according to standard methods before being accepted for use. An interesting instance of construction involving the use of the Colum- bian system of reinforcement was furnished in the case of the Mess Hall of the Midshipmen's Quarters at the U. S. Naval Academy at Amiapolis. In front of the Mess Hall is located the drill ground, and after the hall had been designed it was decided to arrange a series of terraces on the roof in order to furnish seating capacity for spectators watching the evolutions of the cadets. The Mess Hall is 75 x 375 feet inside with two lines of rein- forced concrete columns 25 feet center to center, each way, dividing the en- tire area into 25-foot squares. The roof is made up of groined arches of 25 feet 6 1-2 inch radius. The crux of the problem lay in the fact that the outside walls would not stand any thrust and it was there- fore necessary to design a construction that exerted only a vertical stress upward on the supports. The problem was solved by building the whole roof as a cantilever. The section between the two inner rows of columns was cast solid with a joint in the center, the outside ends of the beam being supported by the joint and outside wall. The Hennebique System This system, which is one of the best known and most extensively used in Europe, was brought out in 1892 by M. Hennebique, who was one of the first to introduce the reinforced concrete beam and is sometimes mis- takenly designated as its original inventor. The floors according to the Hennebique system are formed in several ways, the most commonly employed being the flat single floor with exposed beams. The floor rods are in two series, one bent up to pass over the support near the upper surface of the slab and the other set straight throughout and embedded near the lower surface. The rods are placed alternately, one straight and the next bent up over the supports. The hoop iron stirrups which are a feature of this svstem are placed near the supports to resist the shearing [56] REINFORCED CONCRETE CONSTRUCTION ii II I y [57] REINFORCED CONCRETE METHOD OF TESTING THE STRENGTH OF REINFORCED CONCRETE FLOORS CONSTRUCTED ON THE UNIT SYSTEM TEST LOAD ON A SLAB 7^ INCHES THICK, WITH i l /> INCH STRIP PILING ( See page 336 for description ) [581 REINFORCED CONCRETE CONSTRUCTION stresses. These stirrups pass under the rods, their extremities being slightly bent and terminating near the upper surface of the concrete. Beams are reinforced in the same manner as slabs with straight bent- up rods, but in this case the straight rods are placed near the bottom sur- face and the bent rods above them. The ends of the rods are carried over the supports and some distance into the adjoining beam or wall. The main stirrups of the beams are spaced further and further apart from the sup- port toward the center of the span as the shearing stress diminish in a like manner; a further series of short stirrups is placed over ends of the bent-up rods to firmly secure them to the concrete. When the depth of the beam is too small to obtain the necessary compressive resistance from the concrete alone a further series of straight rods is employed near the upper surface. The beams and floor slabs are monolithic and in consequence the beams are designed as being of T-section. When these are freely supported the bent-up rods are omitted. The walls in the Hennebique system, when the pressure may occur on both sides are reinforced with two series of vertical rods, one near each face. Each set is tied to the opposite face with stirrups, longitudinal rods being placed in the center of the rod. If the pressure will be only exerted on one side of the wall the vertical rods will be placed only on its face. Ferroinclave Sheets of thin steel are corrugated so as to form dove-tail grooves have been used by a number of firms as a reinforcement and centering for con- crete steel, the dove-tailing serving to unite the sheets to the concrete. Under the name of Ferroinclave the Brown Hoisting Machinery Company of Cleveland, have patented a tapered corrugation which is small enough to hold mortar and hence can be plastered on the under side. This material is principally used in the construction of fire resisting roofing, siding, flooring, etc., for factory buildings, power plants and the like. After being secured in place it is always coated on both sides with Portland cement mortar. Ferroinclave is generally made of No. 24 U. S. gauge box and an- nealled sheet steel. Each sheet is accurately crimped by special machinery into the dove-tail section. The corrugations are a half inch in depth of height and are two inches center to center. They are made wider at one end of each sheet than at the other so that sheets may be shingled or fit end- wise into each other. The principal advantage in the use of corrugated sheets for floor construction lies in their ability to sustain the concrete (with moderate spans) before it was set, thus saving the cost of centering and the time required in putting it in place. For roofs, Ferroinclave would seem to be an exceedingly light and cheap form of construction as the total thickness need not exceed i 1-4 [59] REINFORCED CONCRETE inches and it only requires an asphaltic paint over the same to make the roof watertight. With a good coat of hard plaster or gauge mortar on the under side the iron will not be affected by heat until a considerable time has elapsed, and even if the mortar on the under side should be more or less dislodged by the stream of water it can be replaced at a very slight expense. Another advantage of Ferroinclave for roofs is that the building can be covered and made watertight in the most severe winter weather and the cement applied during the following spring. The Turner Mushroom System The promoter of this system, Mr. C. A. P. Turner, claims that in ware- house work it is perfectly feasible to put up a building with columns at 16 foot centers with a floor of 7 1-2 in. rough slabs, using no ribs at all, and test it with 800 lb. per sq. ft. without injury to the construction. Further- more, he claims that it can be put up at less cost without the ribs, and will require less metal, as the load will travel more directly to the supports, instead of around a corner, as in the case where beams are used. The method of construction which he employs is shown in the accompanying illustration/ The small bend in the truss gives them an anchorage in the concrete, which, from Mr. Turner's experience appears to discount any form of wicked-section mechanical bond yet invented. In one instance, iad work, on the part of an incompetent contractor, on a footing gave Mr. Turner an opportunity of judging the amount of distortion, a connection of this character would stand. He found that it would stand, if anything, as great an amount of distortion, without material injury, as could be expected from a structural steel frame with standard riveted connections of the web of the beams to the columns. Such reinforcement is more satisfactory from the standpoint of resistance to lateral or vibratory forces. The Crandall System An interesting application of reinforced concrete was that recently employed in the construction of a slope wall along the Allegheny River at Warren, Pa., for the purpose of protecting the low land adjacent to the river and the important manufacturing establishments at that point from the effects of floods which are of frequent occurance in that locality. A levee, constructed a number of years ago, had proved in- adequate, and the question of adequately protecting this part of the city was therefore a serious and important one, calling for the outlay of a large sum of money. Mr. D. F. A. Wheclock, city engineer of Warren, was employed to solve the problem, prepare plans, etc. and carry out the scheme. His aim was to afford perfect and permanent protection at the least possible outlay. [60] REINFORCED CONCRETE CONSTRUCTION QjH- OX oo w *' [6iJ REINFORCED CONCRETE Breakwaters, stone retaining walls, rip-rapping and reinforced con- crete were considered, and plans and specifications prepared for the different methods of construction. The plans with reference to the construction of breakwaters called for such an enormous expense that they were abandoned ; those for the retaining walls were aban- doned on account of the expense and also the improbable permanence and durability of the work. Bids were asked for on two plans, one for thoroughly rip-rapping the bank of the river against the levee, which was to be repaired and extended for some distance, and the other for a reinforced concrete wall to be built on a slope of one to one and which would not require additions to the remains of the levee. When the bids were opened, it was found that the reinforced con- crete wall could be constructed for about 80% of the cost of rip-rapping and repairing the old wall. The successful bid called for the use of Crandall bars made of high carbon twisted steel, the concrete to be eight inches thick, to withstand a shock three times greater than that which rip-rapping would sustain, with a thickness of from fifteen to eighteen inches. The Crandall bars were accepted after a series of thorough and exhaustive tests. In the construction of the wall, Crandall bars were placed six inches from the face and two inches from the back of the wall and one foot apart horizontally for the whole length of the wall, and also one foot apart vertically all along the slope of the wall. The bars used were of -J-inch twisted steel. As the use of reinforced concrete in that section of Pennsylvania is rather novel, the construction of the wall naturally excited considerable interest among engineers, contractors and others interested in that class of work, and has been pro- nounced one of the most successful engineering feats in that section of the state. The wall is 20 feet high and constructed in sections separated by sand joints every fifteen feet, the reinforcing bars extending through the sand joint into the next section for a distance of twelve inches. This was done in order to protect the wall against cracking; by lapping the bars over the sand joints, the wall was protected at these points against accidents. The concrete was mixed in the proportion of one part cement to six parts of gravel and sand so combined as to fill all the voids. The bars employed in this work were manufactured by Charles D. Crandall, of Warren, Pa. Early American Patents. The first patent to be issued in connection with reinforced concrete construction in the United states was that granted in 1878 to Thaddeus Hyatt on a combination of iron and concrete. This patent virtually cov- [62] REINFORCED CONCRETE CONSTRUCTION \ co-FOOT SPAN SHOWING THE USE OF THE RANSOME TWISTEDJ BARS FOR REINFORCE- MENT OF' CONCRETE FLOORS AT THE RIDING AND DRIVING CLUB, BROOKLYN [63] REINFORCED CONCRETE ered all combinations of steel and concrete in which the steel is provided with obstructions to sliding. However, as a principle cannot be patented, Hyatt's patent covered only the special form of reinforcement described by him. This left the field still open for other shapes. Hyatt, among other things, thoroughly realized that the combination of iron or steel with concrete would be unsuccessful unless the coefficient of expansion was the same. Therefore, in order to thoroughly satisfy himself on this score, he conducted a series of experiments to determine the expansion of the material separately and also when the reinforcement was imbedded in the concrete. This experiment showed the lineal expan- sion of concrete to be .00137 for 180 degrees as compared with .00140 for wrought iron. He furthermore exposed blocks of concrete containing bars of iron to the red heat of a furnace for six hours and found them to be entirely sound when taken out, demonstrating that the relation of the two materials is not affected by expansion or construction. The danger of employing a combination of materials whose co-efficient of expansion is unequal was illustrated in a striking manner during the big conflagration at Baltimore. In a number of buildings, terra cotta was enclosed within steel members. Under the tremendous heat to which these materials were subjected, the terra cotta expanded twice as much as the steel, ultimately causing the collapse of the floors and partitions erected of these materials. Reinforced concrete walls and partitions, how- ever, were found to be in a practically perfect condition, despite the tremendous temperature to which this construction has been subjected. Shortly before the granting of Hyatt's patent, a reinforced concrete building the first in this country had been erected. This was the resi- dence of W. E. Ward, at Port Chester, N. Y., shown in the September issue of CEMENT AGE, which was erected in 1875, and is to-day in as sound and unscathed a condition as it was thirty-one years ago. This building is constructed entirely of concrete, reinforced with light iron beams and rods, the only wood being in the window sashes and door frames, mop-boards and stair-rails. Thus, everything combustible is excluded from the main construction. The Ransome System P. H. Jackson, a civil engineer of San Francisco, was among the first to make practical use of Hyatt's patent in connection with reintorced concrete construction in 1877 and disseminated a great deal of information on concrete construction in general, and reinforced concrete in particular. At about the same time, Ernest L. Ransome, the pioneer of reinforced concrete constrcution in the United States, who had been very successful as a designer and builder of concrete structures in San Francisco, conceived the idea of using square bars of iron or steel twisted their entire length for the reinforcing of concrete, patenting this improvement in 1884. [64] REIXFORCED COXCRETE CONSTRUCTION p O t_, PQ < OPQ z* SUM Q a - oi Si [6 5 ] REINFORCED CONCRETE The bars are twisted cold with a varied number of twists per yard. The effect of this treatment is to greatly increase the ultimate strength and elastic limit, and preventing any tendency toward sliding in the concrete. Beams and floor slabs are constructed together and are fre- quently very similar to those made according to the Hennebique system, except that square twisted bars are used for the reinforcement in the vertical plane. Under Mr. Ransome's direction, a number of buildings were con- structed of reinforced concrete in California, despite the dire prophecies that that form of construction was not adapted to a country subject to seismic disturbances. These prophecies were, however, glowingly dis- proved during the recent earthquake ; while brick and other stone struc- tures in their immediate vicinity were wrecked, the reinforced concrete buildings erected by Ransome passed through the ordeal unscathed, prov- ing that for an earthquake country, reinforced concrete is the safest structural material which can be employed. The only event which could bring about the entire collapse of a properly designed and constructed reinforced concrete building, would be the giving way of the ground beneath it. Even in such a case, unless the flexing strain became unusually severe, the building, due to its monolithic nature, would be very likely to sustain only slight damage. Furthermore, -the conflagration usually accompanying earthquakes would find but little to attack in a building of this type, as was shown to be the case at San Francisco. It is mainly due to Ransome's missionary work that reinforced con- crete construction has reached its present commanding position in building- construction. Through communications to the technical press, the reading of papers before engineering societies, lecturing before architects and engineers, he kept up an active propaganda on the subject and paved the way for the widespread introduction of this new form of construction. An instructive index of the effect of this constant hammering away is offered by the figures showing the growth of the production of Portland cement coincident with the spread of reinforced concrete construction. While in 1890, when Ransome began his crusade, the production was only 300,000 barrels, it had increased to 36,000,000 barrels in 1905, one of the most remarkable instances of results of persistency upon an industry in recent times. The first application of reinforced concrete to factory and mill con- struction on a large scale was in the factory of the Pacific Coast Borax Co.. at Bayonne, N. J., which was erected by Ransome in 1898. The fireproof qualities of the construction were demonstrated by the severe conflagration which it was subjected to some time ago, during which it sustained com- paratively little damage, the high temperatures, increased as they were [66] REIXl'ORCED CONCRETE CONSTRUCTION REINFORCED CONCRETE FACTORY OF THE EASTWOOD MACHINE SHOP, NEWARK, N. J. REINFORCED WITH EXPANDED METAL ROOF OK THE NEWARK WAREHOUSE CO , NEWARK, N. I., REINFORCED WITH EXPANDED METAL [6 7 ] REIXFORCED COXCRETE by the fumes of acid, would have completely wrecked any other type of structure. The Expanded Metal System Another pioneer in the development of reinforced concrete con- struction in the United States was John F. Golding, well known as the inventor of expanded metal. He was induced to experiment with the latter as a reinforcement for concrete slabs, his experiment proving so successful that expanded metal construction has come rapidly into great prominence. Expanded metal is made from mild steel, having an ultimate resistance of 48,000 pounds per square inch and an elongation of 21 per cent, in a length of 8 inches. It is manufactured from flat plates of thickness vary- ing from % to about T /s of an inch, and when expanded, the usual meshes are from 6 inches to 3 inches in width. The operation of making it consists in placing the sheets vertically, resting on their edges. They are then slotted and pulled out at one operation. After being slotted, they are drawn out laterally so that the width of the finished sheet is in reality pro- duced from the height of the original plate when placed with its edge downward. The expansion effect varies from about 6 to 12 times the original width of the plate. However, no alteration is made in the length, the strands being consequently somewhat stretched. A portion is left uncut, thereby forming a strong "selvedge" edge. It has been found that the ultimate strength is increased from 48,000 to about 63,000 pounds per square inch through the operation of expanding. Expanded metal is mainly used for slab construction, although in a few instances, it has also been used in the construction of beams. The Cummings System The characteristic feature of this system, which is being advocated by the Cummings Structural Concrete Co., of Pittsburg, is the use of plain commercial steel shapes for reinforcement. As this steel requires no special molding or rolling, and can be readily procured out of stock, the cost of the reinforcement is naturally reduced to a minimum. By the use of a patented system of bars looped at the ends, a perfect bond is provided with the concrete, without increasing the weight of steel and forming a structure secure against vibration and impact. This would seem to make this system particularly desirable for use in factories containing heavy r vibrating machinery. The loop bars for beams are made by bending and welding round bars into long rectangular frames. The ends of the frames are bent up to resist shearing stresses but the straight part of the frame remains at the bottom of the beam to take its proportional share of the bending movement. The bent-up ends form a looped anchorage by which the steel is self-supporting. At the same time, it cannot be disarranged while the concrete is being- [68] REINFORCED CONCRETE CONSTRUCTION placed. As the shearing reinforcement forms a part of the longitudinal bars, it can be neither displaced nor omitted. The bars of a beam are placed in two layers with what is known as the Cummings chair between them. The bottom layer of the bars passes up between the members of the top layer. The sizes of these bars range from ^ to ^4 of an inch in diameter. The chair is stamped from sheet or bond steel having regular pro- jections which are bent up to space the reinforcing bars and down to hold them in position. The projections are adjusted before the chairs are placed in the materials and the steel reinforcement is then fixed in position. Being entirely imbedded in the concrete, the chair is not seen when the mold is removed. The essential feature of this device is that it insures accurate spacing and fixing of the reinforcing steel in its position. [69] REINFORCED CONCRETE > h [70] AN EXAMPLE OF A BRICK AND STONE VENEER ON A REINFORCED CONCRETE BUILDING; THE BILGRAM MACHINE SHOP, PHILADELPHIA CONCRETE IN FACTORY CONSTRUCTION The demand for concrete industrial plants is rapidly increasing. In this article are shown some ex- amples of modern factories, with a general review of the principles oj construction By . A. Trego AMONG many building types to which concrete has been applied, the modern factory stands as a conspicuous example of its worth. Concrete is peculiarly adapted to buildings of this character. Under the general term economy mav be embraced its almost countless advantages. The latter include fireproof qualities and durability as well as cheap, but none the less substantial, construction. The term substantial construction may itself be subdivided to embrace durability, strength of frame and great weight-carrying floors which are free from vibration. In factories of a certain class even sanitary conditions are achieved at greatly reduced cost over other materials. Indeed, concrete has entered into every feature of modern factory or mill construction, from foun- REIXFORCED COXCRETE dation to roof, and the tendency to-day is more and more in the direction of concrete construction throughout. And while the factory, owing to con- crete, has improved as a building type, there has been a corresponding improvement in the processes of its construction, the introduction of econ- omies which make for greatly reduced cost. In succeeding pages are shown factory buildings of various designs, but all possessing features which indicate the growing popularity of con- crete as a structural material. It is not the purpose here to go into minute detail of mill construction, but rather to show that the concrete factory is a reality and admirably adapted to the purposes intended. Concrete Factories in Philadelphia Among the great manufacturing centers of the United States is the city of Philadelphia, and it is only natural that in that metropolis, which is in close touch with the greatest cement producing district of the country, should be found many examples of the new type of factory. It was some four or five years ago that an enterprising firm of architects and engineers in that city, Messrs. Ballinger & Perrot, discerning the future of concrete, began to give serious consideration to concrete construction as applied to industrial plants. In the brief period designated, they have designed and constructed a large number of plants in Philadelphia and neighboring cities. A GOOD EXAMPLE Of- INTERIOR CONSTRUCTION OF CONCRETEj PLAN'I OF THE BILGRAM > MACHINE SHOP, PHILADELPHIA [72] CONCRETE IN FACTORY CONSTRUCTION CONCRETE BUILDING OF THE CRANE ICE CREAM COMPANY, PHILADELPHIA Concrete in Machine Shop Construction One of the first, if net the first, manufacturing plants in Philadelphia in which concrete was introduced, is the machine shop of Hugo Bilgram, designed and constructed by Ballinger & Perrot. We show an exterior and interior view of the shop. All the floors and the roof are built of reinforced concrete. The wearing surface of the floors is of maple nailed to wooden sleepers, with cinder concrete between the latter. The building is 120 feet long and 100 feet deep. For a little more than half the depth it is two stories high with provision for three additional stories. The interior view shows the substantial character of the concrete work. The building also contains the first saw-tooth skylights erected in Philadelphia which are made of concrete and glass. Crane Company Ice Cream Factory Built of Concrete Reference has been made to the value of concrete where sanitary pre- cautions are essential. In this connection the factory of the Crane Ice Cream Company, Philadelphia, is an interesting example. The name of this company is almost a household word in Philadelphia and vicinity, the extensive business it conducts having been founded upon the excellence and purity of its products. Therefore, cleanliness and proper sanitary precau- tions were important considerations when a new and larger factory became a necessity. That concrete has answered every purpose in this instance, [73] REIXFORCED COXCRETE the President of the Company, Mr. Robeit Crane, will attest. The two views of the factory shown herewith indicate its substantial character. The interior view discloses the immense concrete girders, with a span of forty feet, designed to carry a load of 150 Ibs. to the square foot. Another rea- son fcr the adoption of concrete was the fact that a material capable of resisting the action of salt water \vas necessary. Mersrs. Ballin er & Per- rot conducted experiments along this line by immersing a concrete cube containing steel rods in brine, where it was allowed to remain for seven months. When the cubes were finally broken, the rods were found to be in perfect condition. The building, which covers an area of no by 240 feet, is also roofed with concrete. While the outer walls are brick the entire interior construction is concrete. The various departments comprise the store, offices, sleeping and living rooms, dining room and kitchen for em- ployes, ice cream and pastry departments, shipping and storing depart- ments, and the power plant, the latter including boilers, engines, dynamos and ice making machinery. At the rear of the lot, and entirely cut off from the factory, are concrete stables with the stalls on the second floor. Concrete Plant of the Victor Talking Machine Company A third structure is the plant of the Victor Talking Machine Co., in Camden, N. J. The original plant was of the slow burning mill type, the various buildings forming a hollow square. The exterior view shown herewith is that of a new concrete building containing the executive of- CONCRETE GIRDERS AND COLUMNS IN THE FACTORY OF THE CRAME ICE CRE'XM COM- PANY, PHILADELPHIA [74] COXCRETE IX FACTORY CONSTRUCTION DETAIL OF CONSTRUCTION OF THE CONCRETE PLANT OF THE JEANESVILLE IRON WORKS COMPANY fices and pressing plant. It is the latest addition to the factory. It has a frontage of i/o feet on one thoroughfare and 70 feet on another. It comprises four stories of reinforced concrete with brick walls. The inte- rior view shows the reinforced concrete columns and girder construction. In the power house the engines, dynamos, etc., rest on a reinforced concrete iioor over the boiler room. Xo perceptible vibration occurs in the floors when the machinery is running. The view of the engine room shows rein- forced concrete girders with a span of 40 feet. During a vibration test a coin placed on edge on one of the engines remained in that position while the machinery was in operation. In adopting concrete construction the company was influenced by the fact that it had sustained a serious loss by tire, involving not only the destruction of valuable property but a serious delay in manufacturing. The insurance was materially reduced on the new building. The yeanesville Iron Works Plant The next example of mill construction shows concrete walls finished and in course of construction. The- pictures are exterior views of the Jeanesville Iron Works, at Hazleton, Pa., one a general view of the works and the other illustrating the preliminary bu : l:ling operati?ns involving the use of forms. A very impoitai t circumstance in connection with the building of this mill was the fact that the walls of concrete cost less than brick. There was a great deal of mountain stone or boulders to be re- [75] REINFORCED CONCRETE AN EXAMPLE OF CONCRETE FACTORY WITH BRICK AND STONE VENEER; PLANT OF THE VICTOR TALKING MACHINE COMPANY AT CAMDEN NEW JERSEY ENGINES IN THE CAMDEN PLANT OF THE VICTOR TALKING MACHINE COMPAN f, RESTING ON CONCRETE GIRDERS WITH A SPAN OF 40 FEET 176] CONCRETE IN FACTORY CONSTRUCTION THE UALTIMORE PRINTING PLANT OF THE FRIEDENWALD COMPANY, BUILT OF REIN- FORCED CONCRETE moved and these were utilized in the form of crushed stone for the con- crete, thereby cheapening materially the cost of preparing the site. The expense for this would have been considerable with any other type of wall, saving, as it did, the cost of transporting bricks, etc. In excavating the rock it also proved convenient to establish a large reservoir for pro- tection in event of fire. Altogether the mill is an excellent example of the METHOD OF CONSTRUCTING THE CONCRETE WALLS OF THE PLANT OF THE FRIEDEN- WALD COMPANY, BALTIMORE (771 REIXFORCED CONCRETE economy of concrete construction in an environment such as has been described. A Printing Plant in Baltimore of Reinforced Concrete A three-story and basement building of fireproof construction through- out, with walls, columns, floors and roof all of reinforced concrete, is the Friedenwald Printing House, in Baltimore. The building fronts on three streets, the greatest length being 280 feet with a depth of about 80 feet. A concrete stack 100 feet high and 54 inches in diameter is a special feature of the plant. The structure has attracted a great deal of attention and is regarded as one of the show buildings of the town, public interest being heightened by the fact that it" is concrete. An exterior view of the plant from the drawing of Ballinger & Perrot is shown. A second view shows the forms in place during wall construction. In this building all the moldings and ornamental features are cast in concrete. The exterior sur- face will be dressed with a pneumatic tool. The base of the building and certain other features will be more roughly dressed than the piers in order to establish a contrast in texture and finish. In brief, the architects are seeking to procure a characteristic expression in concrete without regard to brick and stone designs. Concerning the practical features of the building the heavy presses will be carried on concrete floors. An innovation will be the wide \vindow openings, affording lots of light, which is easily accom- plished in concrete construction, and which has been adopted by the above firm as a permanent feature of their factory plans. The unit system adapted to the Kahn bar was employed in the construction of this building. A Substantial Concrete Structure in Philadelphia The early stages of work in the construction of an addition to the glue factory of F. W. Tunnell & Company, Philadelphia, are shown in the accompanying photograph. The building, which is 43 by 104 feet and three stories, is intended for drying purposes. The walls, columns, floors and roof are reinforced concrete. The need for unobstructed space on the two upper floors was easily met with concrete by the introduction of concrete girders with a span of 39 feet, thus doing away with columns. Reinforced concrete cantilevers projecting five feet and carrying the floors and roof of an adjoining building constitute an interesting feature of this structure. d Model Concrete Printing Plant The highest completed concrete building in Philadelphia up to date was designed by the above firm for the Ketterlinus Lithographic Manufac- turing Company. As shown in the accompanying photograph, it is a sub- stantial structure and an addition to an older building. It is reinforced concrete with wall piers veneered with brick to correspond with other parts of the plant. It is eight stories with basement. The reinforced con- crete floors are designed to carry a load of 400 pounds to the square foot. [78] CONCRETE IN FACTORY CONSTRUCTION [791 REINFORCED CONCRETE Heavy presses weighing from 15 to 20 tons are installed in the third, fourth and fifth stories. The absence of the excessive vibration which took place in the old building when the presses were running is a conspicu- ous advantage in the new building, and a striking example of the virtue of concrete in this respect. As a matter of fact the rigidity of the new building when par- tially completed served to decrease vibration in the ad- joining structure. Reinforced concrete columns are used ex- clusively in the four upper stories and on the lower floors with the addition of a steel core to avoid increasing their size. It is said this plant en- joys the distinction of being the only building in the con- gested portion of the city in- sured by the Associated Fac- tory Mutual Insurance Com- panies, which is due to its su- perior construction and equip- ment. The windows have metal frames and wire glass, A Pittsburg Concrete Warehouse and Factory A tall structure, contain- ing offices, warehouse and fac- tory is that erected for the Bernard Gloekler Company of Pittsburg, manufacturers of refrigerators and store fix- tures. It is ten stories and basement, 80x100 feet, and of reinforced concrete through- out, including the walls and ornamental features, except- ing the main entrance and dentil course of the cornice which are artificial stone. It CONCRETE CHIMNEY AT THE C. J. MATTHEWS . . LEATHER MANUFACTURING PLANT is one of the notable examples [80] CONCRETE IN FACTORY CONSTRUCTION A NOTABLE EXAMPLE OF CONCRETE CONSTRUCTION WORK; A TEN-STORY BUILDING OF THE BERNARD GLOELKLER COMPANY, PIT1SBURG [81] REINFORCED CONCRETE DETAIL OF CONCRETE FLOOR, BEAM, GIRDER, AND COLUMN CONSTRUCTION, IN FACTORY OF MERRITT & COMPANY of concrete construction. A tower containing three tanks, two of 5,000 gallon capacity, and one of 20,000 gallon capacity, and a reinforced concrete chimney 48 inches in diameter and 165 feet high, are special features. The whole constitutes a fireproof structure of the most substantial character and its height indicates that concrete is perfectly adapted to structures of the skyscraper type. A Concrete Factory Chimney and Floors Concerning factory details it will be interesting to make special men- tion of the tall chimney and floors of reinforced concrete shown in the ac- companying pictures of the C. J. Matthews Leather Manufacturing plant, Philadelphia. The chimney supplanted a steel chimney, which was not sat- isfactory. The concrete chimney has been subjected to gases and heat for the period of several months without perceptible influence. In extensions made to the plant concrete floors were introduced. These floors exemplify in the highest degree the value of concrete in affording resistance to vibra- tion. The glazing machines were placed on the third floor and are operated with practically no vibration, which was so extreme on wooden floors that [82] CONCRETE IN FACTORY CONSTRUCTION it was necessary tc remove the machines. The vibration of these machines is such that in another plant in the same city they were placed on the ground floor and anchored to stone foundations. In the Matthews plant another interesting feature of the concrete work consists of reinforced con- crete cantilevers, projecting 18 inches, which carry a dividing wall load of 80 tons on each cantilever. All of the factories and buildings described above were designed and constructed by Ballinger & Perrot. The experience of this firm has led them to the conviction that concrete, more than any other material, ap- proaches the ideal in the construction of industrial plants. A Huge Factory of Concrete Blocks in Trenton Notwithstanding the fact that the buildings are but partly erected, the huge plant of the Union Paper Cup Co., at Trenton, N'. J., is worthy of special notice in these pages. This company, of which Mr. Henry R. Heyl, of Philadelphia, is president, will engage in the manufacture of paper cups and bottles on a large scale, a patent product which promises to tax even the resources of the enormous plant. There will be many buildings erected but it is only necessary to state that the main structure is 600 by 50 feet, a second building 220 by 50 feet, and a third, 50 by 50 feet, to give some idea of the capacity of the plant, which is intended to turn out 400,000 paper milk bottles per day. The entire plant will be of concrete block con- struction except the floor in the main building, which will be of wood. In other respects the buildings are concrete from foundation to roof, and will be one story high. Mr. Heyl, who has direct supervision of the build- ing operations, has found upon experiment that it has been possible to ef- fect a saving of 50 per cent, over brick construction by the use of concrete blocks for walls. The blocks have also been used for column construction, rods being inserted in the blocks and the whole grouted with cement. Girders and roofs are of reinforced concrete. The spans in some instances are 50 feet clear. It was chiefly the fireproof properties of concrete which led to its adoption in this factory, but the astonishingly low cost of wall con- struction by the hollow block system is another advantage thoroughly appreciated by the company. The blocks are made at the factory site. Two views of the factory are presented, one a perspective view of early work in the big main building, which clearly indicates its vast size. A second view, taken about the middle of September, shows the work com- pleted up to that period. This plant promises to be a record breaker in the matter of substantial and cheap construction. A Reinforced Concrete Factory in Camden An excellent example of concrete cage construction is shown in the accompanying picture of the Expanded Metal Locker Company's factory at Camden, N. J., built and operated by Merritt & Co., of Philadelphia, [83] REINFORCED CONCRETE engineers and builders of expanded metal fireproof structures. As the company announced when it erected this building: "A doctor who takes his own medicine usually inspires confidence/ 7 and that the company has done in this instance. The structure is a five-story reinforced concrete building, 74 feet by 80 feet, for their own use. Early last summer fire destroyed a four-story building which formed a portion of their locker manufacturing plant at Camden, N. J. The build- ing was used for painting, shipping and storage, the main factory being uninjured. The new building is of "cage" construction, the entire load, including both exterior and partition walls, being carried on columns. The latter and the girders are of concrete reinforced with steel rods. The floors and roofs are of concrete and expanded metal. A comparison of the old and new rates of insurance will be of inter- est. The old structure was a fairly good example of brick wall and wood joist construction, but the insurance rate was $1.63 on the build- ing and $1.94 on the contents. On the new structure the rate is 82 cents on the building and $i on the contents. There is shown in addition to the exterior view of the factory an ex- cellent picture of concrete floors, beams, girders and columns. The sub- stantial character of the work is very apparent. THESE GLAZING MACHINES, WHICH CAUSE EXTREME VIBRATION, ARE SUPPORTED ON THE CONCRETE FLOORS OF THE C. J. MATTHEWS LEATHER MANUFACTURING PLANT, PHILADELPHIA [8 4 ] CONCRETE IN FACTORY CONSTRUCTION INTERIOR VIEW OF A CONCRETE STAIRWAY, SHOWING THE USE OF AN EXPANDED METAL REINFORCEMENT A Cement Storage House Built of Concrete A building of concrete for the storage of cement at the Martin's Creek plant of the Alpha Portland Cement Company, in the Lehigh cement district, is another exemplification of the physician taking his own prescription. This structure, also the work of Merritt & Co., is concrete throughout. The accompanying photograph gives the reader a very clear conception of the building. The building is 387 ft. long by 98 ft. wide and 33 ft. high from the floor to the eaves. The building has no windows, but is lighted from the roof. Cement is carried to it by belt conveyers, and it is so designed that the whole or any portion of the building may be rilled to the roof with cement in bulk without danger of the walls bulging outward. The walls are 12 inches in thickness and are reinforced by 6-inch mesh, No. 4 gauge, expanded metal and by steel rods. At intervals of 10 feet there are reinforced concrete buttresses on the outside of the building. In view of the fact that there would be absolutely no combustible material used in the building, the owners intended at first to use sheathing carried upon the steel trusses. The upper surface was to have been of ordinary felt and slag construction. A few days before the signing of the contract a similar roof on one side of the Alpha stock houses took fire and [85] REINFORCED CONCRETE [35] CONCRETE IN FACTORY CONSTRUCTION was in a large measure destroyed, causing considerable loss through the damage by water to the cement stored in the building. The owners there- upon decided that no wood should be used in any portion of the build- ing and the specifications were changed, so that the new building has a roof of cinder concrete reinforced with expanded metal, having the ordin- ary slag finish on top. This provides a building about which there is ab- solutely nothing to burn. Roof and Stairway of Concrete and Expanded Metal The adaptability of concrete and expanded metal in factory construc- tion has been developed to a remarkable degree in recent years. The combination of the two materials has proven especially valuable as a fire resistant. An interesting example of concrete and expanded metal roof construction is shown and also an illustration of the use of concrete and expanded metal in the construction of a stairway, both the work of Mer- ritt & Company. A Concrete Abattoir Probably few happenings in recent years have so aroused the Ameri- can public and created such wide-spread interest in this country and abroad as recent allegations embodied in the report of government inspectors concerning sanitary conditions at the great Chicago packing houses. In view of what has transpired, the concrete structure about to be described possesses more than ordinary interest. It is the packing plant of the Arbogast & Bastian Co., at Allentown, Pa. The plant was designed by Mr. Percy A. Kley, a prominent Philadelphia engineer and architect. It is said to be the first concrete packing plant erected in the United States, and comprises a number of buildings. The, accompany- ing photographs show the exterior of building A, in which the sausage manufacturing department is located, and an interior view of concrete construction in which round and square columns, beams and girders are shown. The plant consists of six buildings from four to five stories high and of varying dimensions. The largest is approximately 40 by 82 feet. The foundations are concrete and the walls brick. The interior construction throughout is concrete, even to the lintels of doors and windows. The columns, floors, girders, beams and roof are of concrete. The girder spans in some instances are about 16 feet and beam spans 17 feet. In one build- ing the cellar is utilized as the hide department. The general offices and beef killing department are on the first floor. Above these are the cold storage and machinery departments, and on the third floor the hog killing is conducted. The fourth floor is the fertilizer department. All the build- ings are on the same general plan so far as concrete construction is con- cerned. [87] REINFORCED CONCRETE [88] CONCRETE IN FACTORY CONSTRUCTION "\ THE EXPANDED METAL LOCKS FACTORY OF MERRITT & COMPANY, TRENTON, NEW JERSEY; BUILT OF REINFORCED CONCRETE A CONCRETE STOREHOUSE; THE PLANT OF THE ALPHA PORTLAND CEMENT COMPANY AT MARTINS CREEK [89] REINFORCED CONCRETE :u CONCRETE IN FACTORY CONSTRUCTION BUILDING A, CONCRETE ABATTOIR OF ARBOGAST & BASTIAN COMPANY ALLENTOWN, PA.j A MODEL OF THIS TYPE OF CONSTRUCTION INTERIOR VIEW OF THE ABOVE ABATTOIR, SHOWING THE CONCRETE CONSTRUCTION. NOTE THE ROUND AND SQUARE CONCRETE COLUMNS [91] REINFORCED CONCRETE THE REINFORCED CONCRETE MILL AT PASSUMPSIC, VERMONT; BUILT WITHOUT THE AID OF A CONTRACTOR BY THE PRESIDENT AND TREASURER OF THE COMPANY As stated, this is the first modern concrete abattoir in this country. In undertaking its construction Mr. Kley so designed the plant that it should accord in every respect with the conditions prescribed by the De- partment of Agriculture. Special attention was given to the problem of securing many departments in one plant which should at the same time be -entirely independent of each other where necessary to insure absolutely safe sanitary conditions. It was found that concrete was admirably adapt- ed for this purpose. Not only did it lend itself to construction of a durable, fireproof and sanitary character, but was especially valuable in the install- ment of a perfect cold storage system. The Allentown abattoir is a valu- able example of the utility of concrete for the purposes described. A Factory Built Without a Contractor An interesting example of concrete mill construction is the plant of the Passumpsic Fiber Leather Co., at Passumpsic, Vt. Not only is the mill somewhat out of the ordinary, but was built without aid of a con- tractor by Mr. Stephen Chase and his brother, Mr. Theodore W. Chase, who are President and Treasurer respectively of the company. Mr. I. W. Jones, of Milton, N. H., was the engineer and architect. All the stone used in the concrete work was broken by the company's crusher. The plant consists of the main mill, a two-story structure, about 60 by 60 feet, with a reinforced concrete flume; a dry house, office, boiler house and store house. The main building, which is perhaps the most inter- esting, has two concrete floors. The lower floor is on a rock fill and the upper is 4 I -2-inch concrete reinforced with 3-inch expanded metal. This floor is supported by concrete columns 18 by 18 inches. The main girders are 1 8 by 32 inches, and the joists, which are spaced 4 feet 10 inches apart, are 12 by 1 8 inches, with a span of about 14 feet. The girders and joists are heavily reinforced with corrugated rods and stirrups. The floor is planned ' [92] CONCRETE IN FACTORY CONSTRUCTION for a load of 300 pounds and to hold eight large heating engines. The walls below are of reinforced concrete with pilasters above and windows be- tween. The walls of the upper floor are of reinforced pilasters and cap- girder, with brick panels and windows. Above the cap-girders are brick parapets, the roof being supported by steel trusses. The flume, an end of which is a part of one wall of the building, is 20 feet wide inside, and about 50 feet long. The sides are heavily buttressed with a 6-inch panel between. The flume is 14 and 18 feet deep, with 1 8-inch girders over the first part and 22 inch girders over the second part. The latter portion is covered with a 4-inch floor. The end of the flume is 18 inches thick, reinforced with 7-8-inch round rods over 3 inches apart. The end is supported by a iQ-foot arch, 2 feet 6 inches thick at the crown, in which are two holes for draught tubes, and over which the wheels are placed. Over thirty tens of steel rods were used in the building and flume. The First Concrete Plant in New York City The fact that concrete will be one of the important structural materials- in New York City during the next few years is indicated by a contract which has recently been given for the only reinforced concrete office build- ing in New York. This is the first time in the history of the city that permission has been secured from the Building Department for the erection of an industrial structure of this type and the plans which have been made METHOD OF CONSTRUCTION OF THE MILL. THE COLUMNS ARE 18" x 18"; THE MAIN GIRDERS 18" x ji" AND THE JOISTS i" x 18" [931 REINFORCED CONCRETE are being watched with interest by architects, engineers and builders throughout the country. The building will be eleven stories high and will be constructed of concrete throughout. Unlike the majority of concrete industrial structures this building will not be faced with brick. The front of the building will be finished in concrete only in a more careful manner than has been done heretofore with the result that the facade will not suffer in comparison with stone or brick fronts. The finish will be of an honest expression of the construction of the building and will not attempt in any way to imitate any other form of constructional material. The building will be erected on the plot at 231 to 241 West 39th Street for the McGraw Realty Company. The subsidiary concern of the McGraw Publishing Company. The plans were drawn by Radc'iffe & Kelley, archi- tects, who, with Professor Wm. H. Burr, consulting engineer, and Walter S. Timmis, mechanical engineer, have charge of the construction work. The builder is Frank B. Gilbreth. The McGraw Building as it will be called has a frontage of 126 feet 4 inches, and a depth of 98 feet 9 inches. The basement is planned for a press room. The first floor will be used for finishing and shipping the McGraw publications and the second and third floors will be occupied by the office force of the McGraw Publishing Company. The remainder of the building will be rented as offices. FACTORY WALLS OF CONCRETE BLOCKS; PLANT OF THE UNION PAPER COMPANY, NEAR TRENTON, NEW JERSEY [94] CONCRETE IX FACTORY CONSTRUCTION THE FIRST CONCRETE OFFICE BUILDING IN NEW YORK; AN ELEVEN-STORY REIN- FORCED CONCRETE OFFICE BUILDING NOW BEING ERECTED FOR THE McGRAW REALTY COMPANY Particular care has been exercised in designing the columns with beam and girder connections to them. They will be more simple in design than those commonly used and have steel reinforcements of no greater weight than usual but of an inherent stability which will give a strength far greater than has hitherto been secured with the given weight of steel. The details of the structure are also of concrete including all partitions, shaft enclosures and stairways. The doors are covered with metal, the window frames are of metal glr.zccl with wire glass. The equipment of the building [95] REINFORCED CONCRETE generally will be such as to give the greatest fire protection and thus insure the lowest insurance rates. The accompanying diagram shows the front elevation of the McGraw Building. The illustration of the General Creosoting Plant at Somerville, Texas, represents a model tie treating plant erected for the Santa Fe Railroad. The construction of the buildings was somewhat complicated from the fact that all the cylinders and boilers were placed and set, and the buildings erected around and above them. There were times also when the machinery was in service, while being tested, and afterwards actually treating ties, which evidently made it rather inconvenient to work to the best advantage. GENERAL VIEW OF THE CREOSOTING PLANT AT SOMERVILLE, TEXAS The buildings were erected and completed in three and one-half months about the time required to deliver structural steel on the ground, and the cost of the structure was about six per cent, less than the cost of one similarly designed in structural steel with concrete roof and wall slabs. The work was under the immediate charge of C. F. W. Felt, Chief Engineer, Gulf, Colorado and Santa Fe, the buildings being designed and built under his direction by the Expanded Metal and Corrugated Bar Company, R. L. Murphy, Contracting Engineer. The plant of the Dayton Malleable Iron Works, designed by Peters, [96] CONCRETE IN FACTORY CONSTRUCTION 6-| BARS WRAPPED WITH SOFT IRON WIRE EVERY \Z" BOILER HOUSE SECTION A-A CYLINDER AND BOILER HOUSE, CREOSOTING PLANT, SOMERVILLE, TEXAS CREOSOTING PLANT .AT SOMERVILLE, SHOWING THE BOILER HOUSE UNDER CONSTRUCTION [97J REIXFORCED CONCRETE REINFORCED CONCRETE PLANT OF THE DAYTON MALLEABLE IRON WORKS, DAYTON, OHIO Burns & Pretzinger, represents a building with' spans averaging fourteen feet in length, and calculated to carry about 150 pounds to the square foot. This represents a very common type of mill building, in which the main structural members are of reinforced concrete, while the exterior walls are of brick or of concrete block construction. Concrete Factories Previously Described in Cement Age Readers of the CEMENT AGE will recall having seen descriptions from time to time of many factories, mills and warehouses, not included among those described in preceeding pages. For example, there was the Boston Motor Mart, an immense concrete structure in which 7,200 barrels of cement were used to create an inde- structible, fireproof building. This building was described in the August number, 1906. The plans of the Ontario Power Company, constructed throughout of manufactured stone, was an interesting example of the adaptibility of concrete to that process, which is described in CEMENT AGE of May, 1906. The great Bush Terminal factory has been the subject of several inter- esting articles and is a most notable example of concrete work. A fine illustration of the interior view is shown in an article entitled, "Economies. [98] CONCRETE IN FACTORY CONSTRUCTION AN EXAMPLE OF A REINFORCED CONCRETE FACTORY AT AUGSBURG, GERMANY THE WALLS, FLOORS, AND COLUMNS ARE ALL OF CONCRETE AN EXAMPLE OF CONCRETE FACTORY CONSTRUCTION AT NYCOPING, SWEDEN, SHOWING THE METHOD OF ROOF CONSTRUCTION [99] REINFORCED CONCRETE ONE OF THE LARGEST PLANTS BUILT OF REINFORCED CONCRETE IN THE WORLD; THE COMPANY AT in the Use of Concrete," by E. P. Goodrich, published in CEMENT AGE of May, 1906. The remarkable rapidity with which concrete construction may be accomplished constituted the striking features in an article in the March number, 1906, on the St. Croix Paper Co. plant, at Sprague Falls, Maine. This plant included a 2OO-foot concrete dam and three large mills. The Fairbanks Company concrete warehouse at Baltimore, with floors designed to carry 250 pounds live load, was not only a good example of that type of structure, but an interesting illustration of the application of ex- panded metal in concrete construction. This building was described in the November, 1905, number, which also contained an illustrated article on the Quaker City Flour Mills Company's concrete grain bins. Among the many illustrations of concrete factories was that of the Robert Gair plant, in Brooklyn, which constituted the frontispiece of the January, 1906, number of CEMENT AGE. A modern power plant in Baltimore, that of the Baltimore Electric Co., was the subject of a special article in the September, 1905, number. This is an absolutely fireproof structure with floors and roof of concrete reinforced with the Clinton fabric. Concrete conduits are also a feature of the plant. An important detail in factory construction was shown in an illustrated article on the tall concrete chimney of the Tacoma Smelter Company, an immense column more than 300 feet high. An exceptionally good illustration of factory construction is the Pugh Power Building, Cincinnati, a ten-story structure built entirely of con- crete and described in CEMENT AGE for May, 1905. [iool COXCKETE IX FACTORY CONSTRUCTION OFFICE AND FACTORY STRUCTURES OF THE FOSTER-ARMSTRONG PIANO MANUFACTURING DESPATCH, NEW YORK The River-Bed power house and pulp mill at Berlin, N. H., construct- ed under great difficulties, is shown in numerous illustrations and descrip- tive text in the CEMENT AGE of April, 1905. In this plant the concrete is subjected to strains exceedingly severe, but without showing any defects. Some of the work was also done in extremely cold weather. The whole plant is of the most substantial character. An immense plant is that of the Foster-Armstrong Company, piano manufacturers, at Despatch, N. Y., described in CEMENT AGE of De- cember, 1904. Five buildings of similar design, each 250 by 60 feet, was constructed of reinforced concrete. This is one of the early examples of the concrete factory and one that has proved fully the worth of the ma- terial. In addition to the factories cited there have been published innumer- able articles relating to details of their construction. What Time Has Verified In conclusion, it may not be amiss to say that CEMENT AGE derives great satisfaction from the knowledge that its predictions concerning the value of concrete in the construction of industrial plants have been more than verified. It was among the first in the effort to advance an industry that has become one of the greatest this country has ever known. It is in- teresting to recall the period when doubt assailed many who are now among the most ardent advocates of cement and concrete construction. The his- tory of the great evolution would not be complete, however, without tribute to the memory of that eminent authority and leader in the movement for improved fireproof mill construction, the late Edward Atkinson. Sta- [101] REINFORCED COX CRETE tistician^ insurance expert, political economist and advanced thinker, his 'labors, whether in the nature of contributions to cement literature or inves- tigation and practical experiment, were invaluable. It has not oeen t\vo years since Mr. Atkinson, in an excellent contribution to CEMENT AGE of April, 1905, called attention to the fact that the subject of cement con- struction had attracted little attention from the owners and managers of large industrial plants. In his characteristic way he went on to discuss the application of concrete to the dwelling, warehouse and factory, and in conclusion set down the following statements which were prophetic, indeed, in the light of what has since transpired: It now seems to be proved that large works may be constructed of rein- forced concrete within ten per cent, or less of the cost of slow burning con- struction. That such buildings are not subject to as great vibration from high speed machinery, or heavy slow movements. That dwelling houses can be constructed of concrete at less cost than of brick. That large warehouses may be constructed at low cost combining the maximum of safety with durability Such are the apparent conclusions which the writer has derived from the reports of tests and the statement of facts submitted by the large con- struction companies, each on its own behalf. Notwithstanding the almost incredible development of detail in con- crete construction which has taken place since Mr. Atkinson penned the above words, his prophecy covered the whole field so far as the fundamen- tal principles of construction are concerned. And it is with justifiable pride that the CEMENT AGE not only recalls its own verified predictions as to the future of cement and concrete construction, but that its pages con- stitute a valued record of the early efforts and research of such pioneers as Atkinson, Norton, Ransome, Tucker and kindred spirits. Progress has not ceased, and though preceding pages give a compre- hensive idea of what has taken place in recent years, the achievements recorded up to this time will doubtless, a decade hence, seem small indeed. [102] A SURFACE FINISH FOR CONCRETE How a pleasing texture is obtained hy a simple and inexpensive process. Conforms to the plastic character of the material By Henry H. Quimby*, M. Am. Soc. C. E. [In considering concrete as a substitute for brick and stone, perhaps the most serious problem confronting the architect is to obtain a satisfactory surface or finish. Judging from what the architect has had to say, his inability to do this zvould seem to constitute his chief objection to concrete. Therefore, the first matter to be determined is whether any of the countless workers in concrete have succeeded in obtaining a surface which will conform to the architect's conception of ivhat is pleasing and artistic. Would a surface resembling dressed stone or granite (not the familiar "rock-hewn" surface seen in concrete blocks) be acceptable? And if so, would the architect be willing to use concrete if a surface of that character could be obtained, not only by a simple and inexpensive process, but one perfectly adapted to concrete as a plastic material, thus conforming to its character without seeking to imitate other materials? It is zvith the hope of convincing the architect that this is not only practical but has al- ready been accomplished, that these pages are devoted to the subject of surface finish in concrete. That the problem is one of wide-spread interest is shown by the fact that it continues to be the subject of discussion ivhen- ever and wherever concrete construction may be under consideration. The proceedings of architectural and engineering societies and the pages of technical journals continue to treat it as an important but unsolved problem. Some months ago CEMENT AGE, in an article treating of concrete work in municipal improvements in the city of Philadelphia, described an artistic concrete surface obtained by a process devised by Mr. Henry H. Quimby, Assistant Engineer, Bureau of Surveys, in charge of the design and construction of bridges. The description of Mr. Quimby's method of treat- ing the surface of concrete in bridge construction was embodied in a brief paragraph at the close of the article, which related to general municipal work, and doubtless escaped the notice of many who are especially inter- ested in the matter. In making it the subject of a special article a number of photographs are published showing the variety in texture possible to *Engineer of Bridges, Bureau of Surveys, City of Philadelphia. [103] REINFORCED CONCRETE obtain ^vith different aggregates, and also the appearance of finished ivork. Quite a number of experiments have been conducted by the Bureau of Sur- veys with very satisfactory results. The bridges already constructed and treated by this process are well worth the inspection of the architect who still believes it impossible to so treat a concrete surface that it will not ap- pear monotonous and uninteresting. By the simple process hereinafter described it may be given life and texture, and with practically no likeli- hood of staining or '"streaking," so frequently the subject of complaint by the architect. The exercise of due care and insistence upon good work- manship will produce the excellent results obtained by the engineers of the Philadelphia Bureau of Surveys.] THE concrete surfaces shown in the accompanying photographs are easily obtained. The process consists in completely flush- ing the face against the form, removing the form after the material has set but while it is still friable, and then immedi- ately washing and rinsing the surface with water. The washing removes the film of cement which has formed against the mold, and exposes the particles of sand and stone. The appearance then depends of course upon the character of the aggregate in the concrete and the uniformity of its distribution in the mixture. As in well mixed con- crete the cement merely fills the voids between the grains of the sand, and the sand fills the voids between the pebbles or particles of crushed stone, the cement visible in this finished surface is so small a percentage that it has very little influence on the color of the work. A convenient means of securing a well flushed front uniform in tex- ture is to make a fine concrete with the crushed stone or pebbles screened to not exceed say three-eighths inch, and apply it to the face form with a trowel just in advance of the body concrete, and ram the concrete into it or joggle the two mixtures together so as to ensure an intimate union. This fine concrete, or granolithic mixture as it is generally called, may be made of different colored and different graded aggregates for different portions of a structure to compose a color scheme. The appearance may also be controlled somewhat by the extent of the washing, for if the work be done at the right time the washing brush can be plied to remove the mortar to a considerable depth between the stones, leaving the stone in a very decided relief and producing a rough coarse texture which, by the way, seems to be the one most admired by the ma- jority of observers. The time to be allowed for setting before washing must be determined with regard to the nature of the cement used and to atmospheric conditions. Quick-setting cement and warm weather call for removal of form within eight or ten hours. The usual practice in summer, using almost any of the American Portland cements, is to remove the forms on the day following the deposit of the concrete. Of course this must not be done with the [104] A SURFACE FINISH FOR CONCRETE. FIG. I. EXAMPLE OF CONCRETE COMPOSED OF I PART CEMENT, 2 PARTS YELLOW BANK SAND AND ? PARTS %-INCH SCREENED STONE. ACTUAL SIZE 'iw^i^KiM :.' &fT > J'%"- .*<* 2 . A'" " k \ * y ../ y / ^* ; FIG. II. PEBBLE AND SAND CONCRETE WITH SCRUBBED SURFACE COMPOSED OF I PART CEMENT, Z PARTS BAR SAND AND 3 PARTS J-I6-INCH WHITE PEBBLES. ACTUAL SIZE [105] REINFORCED CONCRETE I FIG. III. SAND AND YELLOW PEBBLE CONCRETE COMPOSED OF I PART CEMENT, ^ PARTS BAR SAND AND 3 PARTS SCREENED YELLOW PEPPLES. ACTUAL SIZE 1! m- FIG. IV. GRANITE GRIT CONCRETE COMPOSED OF I PART CEMENT, 2. PARTS BAR SAND AND l PARTS i<-INCH GRANITE GRIT. ACTUAL SIZE 106] A SURFACE FINISH FOR CONCRETE. FIC-. V. EXAMPLE OF CEMENT AND SAND MIXTURE COMPOSED OF I PART CEMENT AND 2. PARTS B\R SAND. ACTUAL M'/.h ,. :.;.# ;^/. - - 4 , . FIG. VI. YELLOW BAR SAND AND CEMENT COMPOSED OF I PART CEMENT AND j PARTS YELLOW BAR SAND. ACTUAL SIZE [107] REINFORCED CONCRETE under or supporting portion of forms for arches and floors where the con- crete is subject to stress, particularly in combination with reinforcement. Concrete that is sufficiently hard to sustain more compression than that due to the superimposed weight of a few of its own layers is too hard to wash. In cool weather when crystallization proceeds more slowly, the washing is practicable two or even three days after laying, and in cold weather a whole week has been found not too long to leave it in the forms when a slow-setting cement has been used. If it should happen that a face has been permitted to become too hard for washing With a brush, the film can be rubbed off with a small block of wood or sandstone with a copious flow of water, but it is, of course, labor- ious and it cannot well be carried to the point of leaving the particles of aggregate in appreciable relief. The nearest approach to the washed sur- face is the effect produced by dressing with a sharp bush hammer and then washing with muriatic acid diluted one half. The acid should be well rinsed off. If the height of the wall to be thus treated is too great to be completed in one day face forms must be constructed to facilitate the remova] of the planking without disturbing the studs or uprights. This is easily accom- plished by setting the studs 8" to 12" away from the face line and support- ing the planks with cleats say 2"Xi" tacked to the studs and the planks. This permits the lower planks to be removed and the washing done while the upper planks are in place and concrete being deposited. With the exercise of very watchful care on the part of the workmen and unremit- ting inspection two different day's work can be joined so that after wash- ing the joint will not be unsightly even scarcely distinguishable, but such work is usually not obtainable throughout a structure, and it is found very easy to obtain thoroughly satisfactory joints by indenting horizontal grooves at regular intervals representing courses, and finishing each clay's work at the apex of a groove. These indentations are made by means of triangular beads on the face forms. Usually the bead is the bevelled edge of a strip set between the face planks and lightly secured to the planks with partly driven toe nails so that, if desired, a plank can be removed indepen- dently of the bead above it, the bead remaining to set the plank upon for the next course. These grooves in the face of a wall improve the appear- ance by relieving the blankness of a large area. It is found practicable to prosecute the work with one course of planks where the capacity of the plant for one day is equal to only one course of concrete. In this way the same planks have been used for many different courses on four or rfiore different structures. The cost of washing depends upon the degree of hardness attained by the face. If it be taken at the right time three or four passages of an ordinary house scrubbing brush with a free flow of water from a hose or sponge will be all that is required, and a laborer should wash say one hundred square feet in an hour if the work is conveniently accessible. [108] CONCRETE BRIDGE AT GRAVER'S LANE, PHILADELPHIA, WITH SURFACE TREATED BY THE QUIMBY PROCESS CONCRETE ABUTMENT FOR SEDGLEY AVENUE BRIDGE, PHILADELPHIA, WITH SURFACE TREATED BY THE QUIMBY PROCESS REINFORCED CONCRETE With a harder surface, such as it is likely to have within twenty-four hours in summer, scraping with a wire brush first will accelerate the washing which may then require from two to five hours for one hundred square feet. Bush hammering will cost probably from five to ten cents per square foot according to the quantity and the outfit. This wash method of finishing has been in use for about three years, and the surfaces are quite as pleasing after the lapse of time as when fresh. As yet no hair or surface cracks have been found in any work that was washed, which is doubtless accounted for by the fact that the only material in which such cracks can develop is removed by the pro- cess. A material advantage in the use of forms that are removable while the concrete is green is found in the opportunity for repairing blem- ishes. Incidental voids can be filled with the same material and bulges can be rubbed off because of its freshness without impairing the finish. The accompanying illustrations are from photographs of specimens of various mixtures. The round baluster which is a left-over from a bridge is composed of i cement, 2 unscreened yellow bank sand and 3 cleaned 1-4 inch crushed dark stone. The square baluster, also a left- over is composed of I cement and 3 uncleaned i -4-inch crushed dark stone, the stone dust forming the sand portion. The mixture was used for the whole body of the baluster in each case, iron molds being used, and the washing done within twenty-four hours. The six cuts repre- senting different mixtures as labeled show the actual size of the orig- inal. It is very important to direct the reader's attention to the fact in all of the concrete surfaces shown herewith the coarse aggregate projects in low relief. It may appear to one person in proper form while to another it may seem sunken or intaglio, as though the surface had formerly been incrusted with pebbles and sand, which had washed away. This is a curious optical illusion governed by the positon of the light as it falls upon the page. If what are really crushed par- ticles of stone or gravel in relief should appear as depressions, turn the picture upside down or in proper position to get the true impression. [no] CONCRETE BRIDGE BALUSTER TREATED BY QULMBY PROCESS. I PART CEMENT, } PARTS UNSCREENED DARK STONE GRIT CONCRETE BRIDGE BALUSTER SHOWING QUIMBY PROCESS. I PART CEMENT, 2 PARTS YELLOW BANK SAND AND J PARTS DARK STONE GRIT VALUE OF CONCRETE AS A STRUCTURAL MATERIAL In this symposium^ prominent engineers and builders give abundant reasons to justify its use in seeking the highest development of the industrial plant \It would be extremely difficult in this day to find a plan for industrial plant or factory in which the use of concrete in some form is not contemplat- ed. The chances are it would be found to constitute the chief features of the structure. There must be sound and economic reasons for its use. In work of this character, the structural types established by experience as best adapt- ed to a purpose are not lightly thrust aside at the dictate of fancy or the im- pulse to experiment. It is, nevertheless, a fact that in a day, so to speak, known and tried materials have been supplanted by concrete. It is for the purpose of presenting to our readers in concise but compre- hensive form the views of eminent authorities on this subject, that the follow- ing contributions have been solicited. They are not theoretical conclusions, but statements based upon the practical work and observations of the authors, to whom CEMENT AGE is indebted for an exceedingly interesting and valuable feature of the factory number.} THE ADVANTAGES OF REINFORCED CONCRETE By Emile G. Perrot [Ballinger & Perrot, Architects and Engineers, Philadelphia] When it is remembered that for heavy construction, where large pieces of timber form the principal means of support, the quality of material has, of late years, steadily depreciated and at the same time become more scarce, designers of industrial plants were perforce obliged to look about for some substitute that would permit of the construction of this class of buildings without materially adding to the cost and at the same time be better than the old method of construction. These conditions we find happily met in reinforced concrete, and the test of years has proven that for all types of building, and especially for the [112] VALUE OF CONCRETE AS A STRUCTURAL MATERIAL factory and warehouse, class, this method of construction far outweighs in all points, the older and less durable type of slow burning and wood constructed floors. Not only for floors and columns is reinforced con- crete adaptable, but for walls as well, permitting much less material in the wall, while it gives added space for windows. This increases the brilliancy of the building, which is a most important feature in industrial plants. The chief points in favor of reinforced concrete are : First : Reinforced concrete becomes stronger with age ; slow burn- ing becomes weaker, owing to the rotting of timbers, etc. Second: Resistance to vibration, increasing the life of and lessen- ing repairs to machinery. Third : Low cost of insurance, and almost entire immunity from fire, thus avoiding loss of business due to shut-down of plant. Fourth: Cheap materials and labor. Materials are found in prac- tically every locality. REINFORCED CONCRETE FOR FACTORY CONSTRUCTION By C. A. P. Turner, M. Am. Soc. C. E. While reinforced concrete was used prior to steel for structural purposes, it is only of late years that it has come into extensive use due to the enterprise of the Portland cement manufacturers in placing at the disposal of the Constructing engineer a material of reasonable cost, reliable, if properly handled, and which bids fair to supplant struc- tural steel in the construction of minor engineering works. It is, then, the question of cost or economy which has brought reinforced concrete into favor, assisted somewhat by the well-known advantages of permanence of the construction, its perfect protection of the steel against corrosion or destruction by fire, and last, but by no means least, to the peace of mind of the builder, the avoidance of complex shop details, and the opportunity for the annoying little errors and endless delays incident to structural steel work. As to its special adaptability, as applied to factory construction, we must consider the following types of factories or manufacturing plants : First, those which are one-story mill buildings, with long-span roofs: for these, reinforced concrete cannot compete, for the main frame, with light structural trusses, and the comparison between a slab of cinder concrete and heavy sheathing is in favor in point of first cost of the sheathing, and concrete must win favor on its merits as fire- [113] REIXFORCED CONCRETE proof construction. Where buildings are several stories in height, to carry heavy loads, say 250 Ibs. per square foot, and the column spacing is from 16 to 19 feet, or more, centers, reinforced concrete can compete, in point of cost, with first-class timber construction, while structural steel skeletons, with timber floors, are much more expensive. The advantages, in addition to low first cost and the fireproof char- acter of the material, are its stiffness, which is much greater than steel or timber construction, its freedom from deterioration a good concrete building growing stronger for many years and the rapidity with which it may be erected. There is little or no delay in getting cement and plain steel rods for the reinforcement, which is quite the contrary in attempt- ing to put up a structural steel or timber frame building. In the arrangements for the shaft supports, it is not quite as easy to make the attachments to concrete construction as to the timber frame, but this difficulty can be avoided entirely by laying out the arrangement of the shafting and machinery in advance, and casting the necessary connec- tions in the concrete. As regards the economy of construction, reinforced concrete, in taking the place of timber and steel frame, as is usual in the adaptation of a new material in place of the older types, h'as been, to a very large extent, influenced by former practice with other materials. For example, some of the older types of reinforced concrete construction would, at first glance, appear similar to wood construction. A building put up in Milwaukee ten or twelve years ago had a floor span of 20 feet, or there- abouts, was arranged with ribs approximately 3! or 4 ins. by 16 ins. deep, spaced 18 or 2O-inch centers,, 4 with a 3-inch floor slab on top. A little computation of the cost of centering for a construction of this character will unquestionably show that the centering cost as much, or more, than the reinforced concrete, in fact every rib or break in the construction is expensive, in framing, cutting up lumber and using up time. As the advantages of reinforcement in many directions, in a composite material like concrete, become better understood, a construction which takes into consideration cutting loose entirely from the ideas and methods which govern the inherent characteristics of timber or structural steel frames, will become more generally adopted, and we may look for flat slab construction without ribs to obstruct light, gather dust and interfere with the convenient arrangement of shafting and pulley supports. Such construction will have the advantage in view of the thicker slab which will be used, of more uniform stiff- ness, better provision for temperature stresses or concentrated loads, be more pleasing in appearance, more economical in materials and centering, will not obstruct light with ribs, be easier kept clean, cost less for centering and require a smaller amount of material for a given strength, as the necessary increase in thickness of the slab will not [114] VALUE OF COXCRETE AS A STRUCTURAL MATERIAL require quite as much material as is at the present time put into rib construction. Evidently this construction has its limits of economy. For very long spans, it is not suitable, but for spans from 16 to 20 feet, it may be used to advantage. Such spans are those commonly adopted in warehouse and many types of mill and factory construction. The illustrations on pages 328 'and 329 give a fair idea of the writer's ideas of this type of construction. The first is a photograph of the rein- forcement before the concrete was poured, showing the flat slab and the arrangement of the steel reinforcement. The second shows a test load of 180 tons placed upon a slab 7^ to 7} inches thick, in the rough, with the usual inch and a half or inch and three-quarters of strip filling. It should be observed that this test load is equal to the weight of the heaviest freight locomotive and tender, when fully coaled and the tank filled with water, and that it occupied a space but little greater than half that which would be taken up by such a machine, and that the deflection of the floor was a scant quarter of an inch under this load. We have called attention to the fact that the centering is no small item in the cost of construction, cutting up and wasting lumber in making beam boxes, and cutting centering between slabs is an item that is gradually increasing with the advance in price of lumber and labor. The lumber that we are getting in this section, at least, for centering, is deteriorating in quality, as well as advancing in price, and it is only a question of a short time, in the writer's judgment, when we will use steel largely for centering; in fact, we have already commenced to employ metal centering and are finding it decidedly economical, as compared with cutting up sheathing. As to the comparative cost of concrete and first-class timber frame, the same contractor bid $10,000 less on reinforced concrete for a whole- sale and factory building 235x165 ft., seven stories in height, column spacing 18 feet by 13 feet 4 inches, capacity of floors 250 Ibs. per square foot, to be tested in concrete with 750 Ibs. per square foot, over a full panel. VIBRATIONS OF CONCRETE FLOORS By E. P. Goodrich, Mem. Am. Soc. C. E. [General Manager Underwriters Engineering and Construction Co.] The reports which are constantly coming in with regard to the effect of the earthquake and fire on San Francisco buildings are showing more and more clearly the hitherto almost unrecognized superior advantages of reinforced concrete for work which is liable to the shock of [115] REINFORCED CONCRETE earthquakes and to the devastating effect of fire. These advantages are described as being "unrecognized," but this lack of recognition was only on the part of the public, and those who had not had actual experi- ence with regard to the fireproofing qualities of concrete, or who had not studied this subject, and the somewhat related one of the ability of reinforced concrete work to withstand shock. Engineers who had given this subject consideration knew that the little concrete work which was in existence in San Francisco before the earthquake would be sure to take the palm, when compared with brick and terra cotta and that it would become the material recognized as being the best for reconstruction purposes. Tests of the Vibration of Concrete Those who had studied the subject of vibration in concrete build- ings knew its value from that point of view, and those who are acquainted with the literature on the subject will recall the results of the tests made by the engineers of the Paris and Orleans Railway Co. in Paris, in which a weight was dropped from a given height on a floor construction made of steel beams with brick arches, and the amplitude and time of vibra- tion of the structure noted. Another weight twice as heavy was dropped from a weight twice as great, onto a reinforced concrete floor, which weighed only 60 per cent, per square foot as much as the brick floor, and the amplitude of vibration was only one-fifth as much, and the vibration lasted only one-third as long as in the case of the steel and brick floor. The New York Times of April 23, (only four days after the earth- quake,) commented in its main editorial upon the description given by a correspondent of the method after which the Capitol of Mexico had been designed, so as to preclude the possibility of damage from earth- quake. The edifice is to be erected with a general skeleton of steel columns and beams, and this entire skeleton of steel will be completely embedded in a concrete made of a light volcanic rock resembling coarse pumice stone mixed with the proper portions of cement. The concrete will be strong enough to support the steel, and this steel will form a gigantic basket work strong enough to support the concrete, and pre- vent cracks forming under strains due to terrestrial disturbances. Long before the San Francisco earthquake, the Japanese had noted the marked advantages inhering in reinforced concrete, and it is under- stood that engineers from that progressive country have instituted a series of tests, in which small structures are mounted upon tables cap- able of being vibrated in the same way in which an earthquake would shake the same structure, and the effect of various kinds and durations of shock carefully studied. The survival after earthquake and fire of the walls of the Palace [116] VALUE OF COXCRETE AS A STRUCTURAL MATERIAL Hotel in San Francisco is in a large measure a demonstration of the value of reinforced work in the withstanding of earthquakes. In it the brick walls are tied together by embedded iron rods, so that the work was practically ''reinforced brick work," in a sense somewhat like "rein- forced concrete/' It is evident that even with the best of workmanship, since brick work is made of separate blocks, cemented together, it can- not begin to possess the advantages of concrete, properly reinforced, in which the whole mass, when properly mixed and deposited, becomes a monolithic structure. The Strength of Reinforced Concrete Floors It would seem that such a demonstration, together with the appar- ently immune condition of the large number of concrete floors in San Francisco still intact, could leave no room for doubt as to the great superiority of reinforced concrete for the rebuilding of San Francisco, with particular regard to the possibilities of future earthquakes. A test to destruction of several of the surviving concrete floor slabs would be a most instructive experiment, especially when studied in the light of their original theoretical supporting power. Long before any reports were received, and immediately after the earthquake and fire, many engineering periodicals prophesied that concrete would show itself the best material to be used in the rebuilding of the stricken city, and it is believed that their prophecies have been proven very likely of fulfill- ment, to say the least. As to concrete, on the side of a fire-protecting or fire-retarding material, the reports being made to the insurance companies stand with- out question. The experts in fire protection connected with the numer- ous insurance companies long ago recognized the value of reinforced concrete buildings from an insurance standpoint, and at the present time probably the lowest insurance rates to be found anywhere -in the United States on mercantile buildings are on a series of tenant factory buildings in Brooklyn, New York, built of reinforced concrete with sprinkler equipment, wire glass supported in metal frames throughout, etc. Without question, that is the type which should be adopted in San Francisco. The attention of fire underwriters has been particularly called by their consulting engineers to the wonderful ability of concrete to pro- tect steel against the effects of heat, and Mr. S. A. Reed in reporting to the Committee of Twenty, at a late date, noted particularly the superi- ority of solid concrete column protection over any form of fireproofmg which contained an air space. Quiet air has always been considered as the most perfect insulator obtainable, but such instances as occurred in tjie basement of the Aronson Building, in which columns buckled, which were protected with air space, while others in the same [117] REINFORCED CONCRETE basement withstood all strains where encased in solid concrete, is ample proof of the value of the latter method of fireproofing. Mr. Reed, in his report, also calls especial attention to the great heat probable in the Bush Street Telephone Building, and how perfectly the steel columns were protected, and even probably supported by the solid concrete encasement, even though the temperature of the column steel may have been so high as actually to soften the structural work. It thus appears that before the catastrophe occurred which devas- tated San Francisco, engineers all over the world were turning to rein- forced concrete as the solution of their difficulties with regard to both earthquakes and fires. CONCRETE IS FIREPROOF, RIGID AND PERMANENT By J. R. Worcester, M. Am. Soc. C. E. Concerning the value of reinforced concrete for factory buildings, I would say that there is no question as to its manifest advantages in incombus- tibility, rigidity, and permanence. There are, however, some disadvantages in its use which must be taken into consideration in recommending this material. These are the treatment of outside walls to insure freedom from cracks and a pleasing appearance ; the size of interior columns where there are a number of stories to be supported ; and the increased weight upon the foundations where the ground is soft. It is probable that as time goes on, we shall learn more with regard to methods of overcoming the above mentioned disadvantages, but now there is plenty of chance for study along this line. THE UTILITY OF CONCRETE By Henry H. Quimby, M. Am. Soc. C. E. [Engineer of Bridges, Bureau of Surveys, City of Philadelphia.] Good concrete can be obtained at a price that permits us to use it in equal volume instead of a cheap class of stone or brick masonry to which it is pro- bably always preferable and induces us to use it in place of a superior class of masonry. Its character enables us to make a more economical and effect- ive distribution of our building material, to the saving of a considerable pro- portion of the yardage. The twin virtues of convenience and economy are attributes to which most credit is due for its popularity as a material of construction. They are [118] VALUE OF CONCRETE AS A STRUCTURAL MATERIAL ~\ also responsible for its use by unskilled designers and constructors and for some consequently lamentable failures. Because probably of insufficient scientific knowledge, and possibly of rank dishonesty, and certainly of gross carelessness on the part of designers, contractors and workmen, uniform and dependable quality is not among its undisputed virtues. Unremitting vigi- lance of intelligent supervision is more vital than the quality of the cement, but it can be secured and a sufficiently satisfactory grade of quality assured for safe designing. Like all other good things, it has limitations and when these are over- stretched disaster follows and conservative designers continue to hesitate. But it is scarcely a dozen years since some of the most responsible engineers looked askance at steel, even with its price lower than that of wrought iron, using it only long after their bolder brethren had offered to manufacturers ample opportunity to demonstrate its reliability. So concrete will win as it continues to stand up to its work and as its remarkable adaptability becomes more widely recognized. Good concrete has fair compressive strength, usually all that is needed, though it is not comparable with that of good stone, but is comparable with that of well built stone masonry. There is no longer any doubt of its excel- lent fire-resisting quality when made with a proper aggregate. Its weak- ness is in its low tenacity and consequent low shearing value. The meas- ure of resistance to cracking of well bonded stone masonry is that of the stone itself, while the resistance of concrete to cracking is principally the adhesion of the mortar to the surface of the stone particles which constitutes the cohesion of the mass, the crushed stone being too small to furnish any appreciable bond. The liability to cracks rupturing the body impairing the structure is the principal cause of such distrust of the material as exists among engineers and architects. A judicious use of steel rods can gener- ally be depended upon to counteract the tendency to cracking for the rods can be placed so as to provide the necessary resistance to disrupting forces whether they be internal stresses produced by shrinkage, or external ones caused by unequal settlement of foundation or by direct loads. Some dislike of concrete is due to the unsatisfactory surface finish so commonly given to it, which is an application of neat cement brushed on like paint or rubbed on with a float, and, while sufficiently uniform to be pleasing to the eye, becomes very unsightly in a short time through the development of surface cracks and their absorption of moisture, and some- times even the peeling of the coat. This condition can be avoided and the objection removed by the more modern method of finishing the surface by removing the film that forms against the mold. This can be done at very little cost in most cases by taking the forms away while the concrete is still green and washing ofY the film with a brush and water, and when the forms can not be removed until the work is hard the film can be removed by tool- ing-bushhammering, which, on a good sized job, will cost about five cents [119] REINFORCED CONCRETE per square foot of surface. This treatment exposes the sand and grit show- ing the actual texture of the material giving it the appearance of stone, and as surface cracks never appear in it, should influence the adoption of con- crete in construction where appearance is a consideration. ADVANTAGES MORE THAN OFFSET OBJECTIONS TO CONCRETE By Dean & Main [Consulting Engineers, Boston, Mass.] Because of the inflexibility of the construction and the trouble and expenses involved in adapting it to changed conditions, the progress of rein- forced concrete in supplanting slow burning construction in textile plants, where reorganization and changes to meet new methods must continually take place, will be slow. Among the chief difficulties encountered may be mentioned : Changes in the location of shafting ; proper fastenings and supports for machines when re-located, and the tiresome effects upon employes who are obliged to stand or walk upon such a rigid and inflex- ible surface for any length of time. On the other hand, the growing- scarcity and the corresponding increase of cost of lumber, suitable for mill construction, as well as reduced risks from fire, will tend to bring the construction into more general use, in spite of the obstacles before named. With the existing high cost of brick and lumber, the cost of rein- forced concrete compares favorably with that of slow burning construction, the former probably being no more than five per cent, in excess in ordinary cases. In cases where duplication of forms enter to any extent, and where sprinkler systems may be omitted, this excess is often reduced to nil. As affording a brief idea of the use of reinforced concrete for indus- trial purposes, we offer a partial list of work we have designed and placed under construction this season : American Woolen Co. dye house, Lawrence, Mass. A building 530 ft. long, in ft. wide, designed for six stories. The adaptability and advan- tages found for concrete construction were : Saving of 20 feet of back- fill, as well as deep foundations; immunity against deterioration caused by dampness and acids ; heavy concentrated loads on beams and floors, easily cared for by braces molded between beams and columns. Lawrence Duck Co. building, designed for storage and textile pur- poses. This structure is 188 ft. long, 65 ft. wide, five stories high, with girders over existing flume carrying building and tower walls. The advantages are: Avoidance of deep foundations, reduced cost, making renewal of flume easy ; more durable than steel beams in damp locations. [120] VALUE OF^CONCRETE AS A STRUCTURAL MATERIAL The Simonds Manufacturing Co. building, Chicago, 111. Construc- tion work comprised the office and an extension of the manufacturing- building. The Rosamond Woolen Co. mill, at Almonte, Ontario. The building is a weaving mill, one story, 208 ft. long, 75 ft. wide. The advantage was reduced cost over masonry walls ; equally adapted to retard radiation. Dominion Textile Co. plant, Montreal, Can. Operation consists of a cotton storage warehouse, 120 ft. long, 100 ft. wide, eight stories. (Build- ing now under advisement.) The Woo4 Worsted Mills, Lawrence, Mass. This plant includes the entrance building, 85x35^., columns, steps, floors, roof, and balustrades, wool scouring and wet finishing departments, 242x119 ft., reinforced con- crete floors with supporting columns, also columns and beams for floors above. The dyeing department is 176x119 ft., with floor, columns, beams and braces for a 32-ft. story. The power house is 144x75 ft., reinforced concrete roof and purlins. The boiler house is 270x31 ft., concrete floors, beams and columns. We might also cite a miscellaneous lot of concrete work connected with this mill, consisting of two-foot bridges, trucking passageway, 418x18. ft., toilet room floors, wire towers, pipes and wire tunnels, 4O,ooo-gallon water tank, 1,700 linear feet of hot air ducts, etc. The Penman Manufacturing Co. plant, Paris, Ontario, includes 200 feet of headrace, no feet of tailrace, and floor of wheel-room. At the W. F. Rutter & Co. plant, Lawrence, Mass., a pipe shop 60 ft. long, 27 ft. wide ; floor and supporting columns, designed for loads of 700 Ibs. per sq. ft. of floor surface. REINFORCED CONCRETE IN MANUFAC- TURING PLANTS By Leonard C. Wason [Aberthaw Company, Concrete Engineers and Contractors, Boston.] The large and diversified use of reinforced concrete in mill con- struction in the past has been very gratifying to those interested in the design and building of this type of structure. But the very rapid increase in its use, this year, has been a great surprise, and unlocked for by the writer, although closely identified with this industry. Especially noteworthy is the fact that the initiative has in every case been taken by the mill owners themselves, who, without technical knowl- edge of the material, have recognized its merits and desired its use. Within the writer's personal practice, reinforced concrete has been used "either for floors or for the entire structure of wood pulp and linen [121] REINFORCED CONCRETE rag paper mills, chemical works, wool scouring, dyehouses, laundries, ice cream and soap factories, where waterproof and rotproof floors were needed, both for the lightest and for heavy loads; also where dry, dustless floors were wanted, as in jewelry, spectacle, textile and mills, hardware, machine foundry, and paint shops, where live loads varied from 50 to 800 Ibs. per sq. ft. It has been used for many other manufacturing pur- poses, but the above enumerated list is sufficiently diversified to show that it is suitable for every type of manufacturing building. Inasmuch as in the majority of these mills, cost was the prime con- sideration, it is clear that reinforced concrete can compete with the older types of mill construction ; not in every case with light loads because this material is especially adapted to heavy loads, and therein the greatest econ- omy can be obtained, but, all advantages considered, then its net econ- omy in its use. In adapting this material to factory use, there is greater latitude than is possible with brick and wood in the design of the building, as floors can be built with spans varying from 5 to 50 ft., and loads from 50 to 1,000 Ibs. per sq. ft.; and the walls may either be piers and beams, the space between being filled in by thin curtain walls and windows, or it may be a solid earing wall throughout. Floor finish may be granolithic, asphalt, wood or other material as desired for special purposes. Arrangements can easily be made for the support of line shafting and machinery from walls, columns or ceilings ; and on account of the rigidity of the reinforced concrete construction, which is one of its essential features, there is absence of vibration in the building, which is considered a desirable feature by the manufacturing cor- porations. Referring briefly to details of design, a reinforced footing enables us to get a large spread on the ground, thereby avoiding dangerous settlement with a very limited depth of excavation, and economy is gained by the saving of excavation, the small amount of material in the footing, and frequently by the avoidance of pumping ground water. The writer prefers footings octagonal in plan, bars running in two principal directions, with a few running diagonally to support the small between the two pre- vious sets. Columns may be kept of reasonable dimensions by using rich mix- tures. The writer has used as rich as I part cement to i part stone, with a working stress of 1,200 Ibs. per sq. ft. at the age of one month. This same mixture would have to be used through the thickness of a floor, as well as in a column, in order to obtain necessary strength. Steel bars are used as a precaution against flecture only, being set vertically, one near each corner. If used to carry load in connection with concrete, their stress is so low as to destroy economy. .Hooped columns should never be used because when built with hoops these are never brought into stress, because *. - - VALUE OF CONCRETE AS A STRUCTURAL MATERIAL the concrete, in setting, has a tendency to shrink, and in order to bring the hoops to a stress which makes them carry part of the vertical load, the concrete must be stressed way beyond its safe working limits, which of course should never be done. In floors of long span, the writer, six years ago, made a very careful analysis of the spacing for maximum economy, considering all the elements of design, cost of lumber, concrete, carpenter and concrete labor. Three feet from center to center of beams was then found to give maximum economy. Under existing conditions, this would be somewhat increased, probably approaching four feet. In mill construction, this spacing, how- ever, is more likely to be determined by the conditions of design of mill than by those of maximum economy of floor. However, the difference in cost for spacings of eight to ten feet with a flat slab between, which is common in mill construction, does not increase the cost to a prohibitive amount. So much has already been said on the detail of beam design, both in theory and practice, it is unnecessary to add more to the discussion within the limits of this article. Every week produces new examples of the application of reinforced concrete to mill construction and adds to the advantages shown by experience, until, to-day, considering both first cost, maintenance, and the special requirements of the mill construction, the number of industries to which this material cannot be profitably applied are exceedingly few. This subject would not be complete without reference to the exten- sive use of reinforced concrete at the power development end of the manu- facturing plant. Some of the largest chimneys now in use are of rein- forced concrete, and some of unusual design as a spark arrester where the chimney rests on the roof of a chamber elevated high in air, have been successfully built. Gravity dams, head gates, and pentstocks are coming into such gen- eral use as to require no extended description. Their economy and sta- bility are far greater than the solid type of dam construction, and are entirely watertight. CONCRETE IN BUILDING CONSTRUCTION By E. S. Lamed, C. E. [Member American Society for Testing Materials and Cement Users' Association.] ,The present extensive use of this material is the direct outcome of conservative, patient and persevering efforts of constructing^ _engineers. UNIVERSITY OF ^ TMEKT OP CIVIL REINFORCED CONCRETE The many advantages of reinforced concrete have only recently come to be generally recognized. The use of the material, in the infancy of this industry, was not only a question of its relative economy, but also depended upon the capacity of architects and engineers to design for the many con- ditions that must be successfully met. Happily, and to the great and everlasting credit of the pioneers, the first example of this type of construction proved successful from a struc- tural standpoint, and the influence of this work has gained weight with time, and for several years past the material has been recognized not only as a structural possibility, but its more extensive and universal use has only been limited by natural and commercial conditions. Architects and constructing engineers are coming generally to recog- nize the necessity of equipping themselves for this class of construction, but, of course, until this is accomplished, many will be obliged to design in, and use other materials until they feel competent to use concrete. It seems to the writer that the general public, in their demand for concrete construction, are considerably in advance of the professions directly interested, and in many cases are greatly disappointed to find their architects unprepared for the work desired. This is further emphasized by the fact that many examples of concrete construction it: progress to-day are modifications for designs in stone, brick, timber and steel. The specialty companies engaged in concrete building construction have found it necessary to employ specially trained technical men to submit designs and prepare details for the approval and acceptance of architects, and during the past year these companies have been so overloaded with work that they have been obliged to turn aside many pressing inquiries, that under the circumstances could only be met by contractors experienced in the old style construction. It must be conceded that the enormous growth in the use of reinforced concrete consturction is largely due to the influence of these specialty companies, who have at their command men trained in the technique and an organization experienced in the handling of this material. In the past few years, it has been found that municipal building com- missions have through their inertia placed many obstacles in the way of the more general adoption of this style of construction. In Boston to-day the building laws recognize, to a very limited extent, concrete for building constructon, yet for several years past, by referring requests for permits to construct in concrete to the Board of Appeal, approval has, without exception, been given, and many notable examples of reinforced concrete construction may be found in the city to-day. Among the many special utility applications of reinforced concrete construction may be cited buildings for general factory and warehouse construction, cold storage, markets, packing and slaughter houses, the advantage in the material being found not alone in its fireproof qualities [124] VALUE OF CONCRETE AS A STRUCTURAL MATERIAL and great carrying capacity in the floor construction, but also in its clean- liness and sanitary conditions. The superiority of concrete, in exposure to conflagrations and earth- quake disturbances, has been so emphasized in the experience of Bal- timore, Rochester and San Francisco that to-day no doubt remains in the minds of experienced and discriminating observers and its extensive fur- ther use is sure. Where fire risks are great and the value of merchandise carried on the different floors of large retail, wholesale and storage mercantile estab- lishments is important, the value of concrete floors which are essentially waterproof, has been demonstrated in localizing damage due to fire and water, and its use for floor construction alone will afford large and grow- ing opportunities for experienced construction companies in work of this nature. Much has been accomplished in the past few years tending to reduce the cost of concrete construction through the simplicity of design and erec- tion of forms, yet much remains to be done, and progress is constantly being made in this direction. Among the more conservative construction engineers, we find a belief that it is difficult to secure satisfactory and artistic treatment of exterior surfaces. This, to some degree, is warranted, but is chiefly due to the inexperience of contractors or engineers themselves in this department of the work. It is generally agreed that imitation should not be attempted, and that concrete structures should be given a treatment original, simple, and in entire keeping with the nature of the material itself, by the careful selection of aggregates, care in the proportioning, mixing and placing, the use of pneumatic tools, the sand blast or the mason's float trowel, and in combination with ornate and colored tiles, the exterior surfaces of build- ings can be given a finish harmonious and pleasing to the eye, and artistic to a degree that will excite a general desire for this material, not alone for mercantile and manufacturing uses, but for residential purposes as well. In considering the cost of concrete construction, architects and engi- neers have oftentimes been deceived by the apparent saving resulting from lean mixtures. The cost of cement per cubic foot or cubic yard of con- crete is relatively small compared with its cost in the completed work, and the many advantages of the rich mixture of cement in adding to the compressive strength of the material, its fireproof and waterproof qual- ities, and in overcoming the inequalities of imperfect mixing and placing, are now coming to be appreciated. It has always seemed to the writer curious that mechanical mixing of concrete should have been brought about more through the influence of contractors and the manufacturers of mechanical mixers than the demand of engineers and architects Ordinary hand-mixing of concrete is at best imperfect, and so many different systems of combining the materials are [125] REINFORCED CONCRETE in use to-day that uniform results could not be expected. For light work and reinforced concrete work in particular, mechanical mixing should be insisted upon. For in combining cement, sand and stone, and reducing to a plastic condition, it is necessary to mix not only thoroughly but vig- orously, as only in this way can the cement and sand which forms the bind- ing medium be brought intimately together. In general, competent inspection, independent of the contractors inter- ested, should be encouraged in all concrete construction, not only to see that the materials are properly proportioned, mixed and placed, but also to be prepared to report to the designing architect any conditions that may arise which call for special treatment. . The value of cooperative work, such as has been inaugurated by the American Society of Civil Engineers associated with the American Society for Testing Materials, and Railway Engineering and Maintenance of Way Association, together with the Association of American Portland Cement Manufacturers cannot be overestimated. The assistance of the United States Government in the investigations and experiments now in progress will give the results obtained a significance and value far exceeding anything that has yet been under- taken, and of course it must be recognized that the subject cannot be disposed of in a short time, but it is believed that the results will lead to a gradual standardization of work that will prove beneficial to all interests concerned. The value of National bodies interested in the use of cement must also be recognized, and contractors, architects and engineers would find it greatly to their advantage to be affiliated with such organizations and bene- fit in the exchange of ideas. Nothing in labor conditions can be advanced to the detriment of con- crete construction. Common labor, under 4 competent and experienced supervision, can perform the work with entire success, and while it is believed and hoped that men specially trained in this work will increase in numbers and receive a just and fair compensation, it does not seem likely that the work will ever come under the domination of trades unions or be subject to the delays of sympathetic strikes. The writer would throw out the suggestion to intending buiders, that the removal of reinforced concrete structures will not prove an easy task r and on city property in particular, where the use of buildings is constantly changing and expanding, it would be wise to look ahead a few years, and if possible, prepare foundations to carry a taller and more elaborate struc- ture than may be called for at the present time. It may be cheaper to do this than to wreck and remove a building of this nature. [126] I'.ILUE OF COXCRETE AS A STRUCTURAL MATERIAL CONCRETE CONSTRUCTION, RAPID, ECONOMICAL AND EASY By Chester J. Hogue, C. E. [Constructing Engineer, Boston, Mass.] Reinforced concrete of all methods of building construction, seems to be attracting the most attention just now, and the design of reinforced concrete certainly furnishes, at this time, the best field for discussion of any branch of structural engineering. Reinforced concrete factory construction, from its ease and economy of execution, rapidity of erection and fireproof qualities seems to be the most distinctive development of this form of construction, and in a short description of a typical concrete factory building the writer may mention briefly the principal points of interest and advantage in this particular method of building. On the side of economy, the company with which the writer is con- nected has this year, by careful laying out of the work and study of the wood forms, proven beyond a doubt that a building of this construction can be built at the same cost as one with brick outside walls and wood- framed mill construction interior, and sometimes for even less if the build- ing is high and the loads are great. In general, economy in design lies in using slabs of 8, 10 or 1 2-foot span, supported by lines of beams in one direction only, these beams resting directly on columns with no girders; but when a wider spacing of columns is required, economy is gained by using a slab of minimum thickness, say 3 inches, if the finished floor is to be of wood on top of the concrete, or 4 inches, if the finished floor is to be of granolithic laid at the same time and as a part of the floor, spacing the beams as closely together as this slab will require, and framing the beams into girders at the third or quarter points. In construction, the great point in saving of cost is in uniformity of detail and in making the wood forms carefully at first in units, and then using the units over and over again as many times as possible. As for speed, we can safely guarantee to complete a building at the rate of from eight to ten days a story, and we have this year begun and completed build- ings while other buildings of equal size were waiting for their steel frames to be fabricated and erected. It is shown beyond doubt that in recent fires and earthquakes buildings constructed wholly or in part of reinforced concrete gave the best account of themselves ; if properly built there is nothing to rot or rust ; without hol- low spaces there are no retreats for dust, dirt or vermin. One point, however, shown by a number of recent failures, sounds a [127] REINFORCED CONCRETE note oi warning, quite independently of the feeling of those who have put years of study into this work, that they alone should he trusted to do it, that unless engineers and architects are themselves experts in reinforced concrete design and construction and wish to give their work very careful super- vision, they should be extremely careful that the men into whose hands they intrust the erection of their buildings should know how to design them, how to build them, and should care to do them right, and both they and owners should realize that first cost does not always mean ultimate economy. There are two types of reinforced concrete factory construction, the one with concrete outside bearing walls with few openings, the other [128] VALUE OF CONCRETE AS A STRUCTURAL MATERIAL the skeleton type of constructing, the walls being simply filling in panels ouilt afterwards. It is the latter type in which the writer is particularly interested, because it is the easier to build and the more economical. The illustration of a part section through a typical building of this sort will serve to call attention to the following points: The column and pilaster footings only need go down to a solid bear- ing unless an excavated basement is required. Where there is a basement, light walls reinforced horizontally from column to column, or verti- cally from the basement floor to the first floor will retain the earth, the reactions being taken by the columns or by the basement and first floors, while the walls may be reinforced to carry themselves from footing to footing, requiring no foundations of their own ; where there is no base- ment, the outside walls need only go far enough down to prevent frost 'working in under them, with possibly a shallow trench filled with cinders lor gravel underneath, and can be reinforced to carry themselves from pier to pier, and to support the walls above. By building the footings first and carefully filling, setting and leveling the earth, and laying the floor on the ground, the shores to support the false work can be cut of even length, and there will be a good even surface to shore from. Columns and floors are built first, as in skeleton steel construction, and the outside panel walls are self-supporting, but not weight-bearing, and are built in between the pilasters entirely independently of the floors, and, at a later time, fur- nishing a convenient method of keeping the concrete gang busy while the concrete floors are setting or the wood forms are being shifted from floor to floor, or when the weather is too wet or too cold to safely permit the laying of the more important work of the floor construction. There has been a tremendous development in this class of buildings of late, and probably half of the work in reinforced concrete this year has been of this sort, while the prospects for the future are still better. SPEED IN THE ERECTION OF CON- CRETE BUILDINGS , . ; By '; .; |||;J J. G. Ellendt [Superintendent of Concrete Construction for Frank B. Gilbreth] Modern and up to date manufacturing concerns find it necessary fre- quently to increase the capacity of their plants at very short notice. When this occurs new buildings and machinery are wanted rapidly. The produc- tion of things is those turned over to capable and energetic contractors who are able to get them in spite of difficulties. To battle existing conditions and produce results at a minimum and specified time. The manufacturer regulates his output accordingly, promises deliveries [129] REIXFORCED COX CRETE UNDERWRITERS' UNIT FRAME REINFORCEMENT EMPLOYED IN THE CONSTRUCTION OF THE VALE & TOWNE BUILDINGS, AT STAMFORD, CONN. and makes contracts, dependent upon having his additional plant in opera- tion at that specified time. It is easily seen that it is of vital importance first of all to look for speed in his undertaking and also get the very best style of construction in his buildings and those most suitable for his purpose. The Yale & Towne Manufacturing Co., of Stamford, Conn., recently had the above conditions to meet. Careful consideration and investigation of the style of construction to be used for their new building convinced them that reinforced concrete construction was not only more economical but superior in every respect to their old mill constructed buildings. It was decided there- fore that two of their new buildings, one 60 x 190, and one 50 x 60, both five stories, were to be of reinforced concrete construction, while the third, 60 x 190, also five stories, was to be of mill construction. This latter was intended to save time. As an option on the necessarv lumber had been obtained with prospects of good deliveries. Actual building operations were started the latter part of February on all buildings. While the architects were still designing the buildings and getting ready their plans, all the foundations were put in, from preliminary sketches and information. While this was going on and while the plans were being completed, all preparations for the superstructure were made. Materials were rushed to the building site and the concrete mixing plant installed. A temporary carpenter shop with power saws, planer, drills and other nec- essary machinery was put in operation and forms and centering prepared for two floors of each of the reinforced concrete buildings. [130] VALUE OF CONCRETE AS A STRUCTURAL MATERIAL In order to make the new buildings conform in appearance with the old plant, the exterior walls were designed to be built of brick. This neces- sarily caused another possibility of slow building operations for the concrete buildings, as it is a well known fact that with brick layers and concrete men operating at the same time, not only care must be exercised in keeping har- mony amongst the opposing trades, but to work them continuously without either gang ever waiting for the other. In the erection of these particular bulidings these points were carefully studied, and worked out so well that actually each gang was driving the other. Brick -work was first started on the larger concrete building, and while the walls were being laid for the first story the false work erectors were set- ting forms. Both forces were concentrated at one end of the building and several bays finished to receive the reinforcement rods for girders, beams and slabs. Due to the style of reinforcement used the Underwriters' unit frame the time for placing the reinforcement was cut down to a minimum and the exact location of the reinforcement assured by means of the separators which hold the various rods in their respective positions. The slab reinforce- ment was also made up of units of such size that four men could handle them. All of these units were bent and assembled at a factory and delivered on cars near the building site ready to be placed. As the placing of the reinforcement took but a trivial amount of time, the concreting gang followed the heels of the bricklayers and false-work erectors without interruption. It was found that an entire floor could be con- creted in four days, but that the brickwork and false work erection could not be done in less than eight days. This practically set the time limit on the construction and the remaining stories were erected at this rate. The smaller concrete building was being erected at the same time with its own gang of bricklayers and false work erectors, but the same concrete gang took care of it. This arrangement kept every gang on the jump with the advantage of each gang driving the other with intent to show the possible weakness of the other. Aside from an unavoidable strike on the part of the bricklayers for a few days, the entire operation ran as smoothly as intended. The erection of the mill construction was going on at the same time. The time required to build a story there was found to be just as long as for the reinforced concrete buildings. .A slight saving "of time, however, was experienced as the last floors could .be occupied immediately, whereas in the concrete buildings the centering had to remain for a required time. Sixty-four days elapsed from the time when ground was broken for the buildings until they were ready for operation. The entire work was done by Frank B. Gilbreth, 34 W. 26th St., New York, on the cst-plus-a-fixed-sum basis ; the concrete work was executed by the Gilbreth concrete department, the Underwriters' Engineering and Construction Co., 1170 Broadway, N. Y. [131] REINFORCED CONCRETE REINFORCED CONCRETE MILL BUILDINGS By A. E. Lindau, Associate Am. Soc. C. E. To the uninitiated the whole subject of reinforced concrete seems a hopeless tangle. Each individual designer appears to have his own theo- ries and methods of construction, new formulae are continually being pub- lished by the technical journals, and even the most reliable experiments have so wide a range of variation that the inference is sometimes made that results can be made to fit any theory by a little manipulation. This confusion has arisen, no doubt, to a certain extent, because of mystery with which so many of these so-called systems are surrounded, and fur- ther, because of the changes which have naturally taken place during the rapid development of this comparatively new form of construction. As a matter of fact, however, there is not nearly so great a difference between the various theories and formulae as may be supposed, the differ- ence being principally a question of unit stresses, a condition that prevails in the domain of structural steel design to an almost equal degree, and if the results of experiments on reinforced concrete beams are reduced to the same basis with respect to the percentage of reinforcement, elastic limit of the steel and strength of the concrete, the average result will very closely approximate the values obtained by computation when the loading is such that the bending moment can be definitely determined. The design of mill buildings differs from that of ordinary warehouse construction, in so far as length of span of girders, vibration and shock of sudden loading is concerned. Reinforced concrete girders can generally be made of sufficient span to satisfy ordinary requirements. If necessary, some girders and exceptionally heavy beams can be made of steel protected by concrete. As to vibration and shock, it seems that reinforced concrete can more than hold its own. Many western railroads are using compara- tively thin reinforced concrete floors immediately under a foot or so of ballast. The vibration and shock in a 5O-foot or 6o-foot girder with a train speeding over it 60 to 70 miles per hour must be very much greater than any that is likely to occur in a mill building. In an office building recently erected several concrete lintels, weighing approximately a ton each, were accidentally dropped from a height of five or six stories, on n 4-inch slab spanning 12 feet, without in the least injuring the slab, while the lintels were entirely .demolished. In another instance, a 35-foot or 40- foot length of 1 8-inch water pipe fell, during erection, on a reinforced concrete floor without doing any visible damage to the floor. [132] MISCELLANEOUS ILLUSTRATIONS < w M a [133] REINFORCED CONCRETE [134] MISCELLANEOUS ILLUSTRATIONS 20-TQN PRESSES RESTING ON A CONCRETE FLOOR,' KETTERLINUS BUILDING. PHILADELPHIA REINFORCED CONCRETE WAREHOUSE OF THE VICTOR TALKING MACHINE CO., DALLINGER & PERROT. ARCHITECTS [135] REINFORCED CONCRETE 3 W w o o H W IH ? w 3 u -^ g o g fe O fe en < 8 fc ffi en en y M O B MISCELLAXEOUS ILLUSTRATIONS LAYING EXPANDED METAL ON CENTERING, FAIRBANKS CO. WAREHOUSE, BALTIMORE, MD. EXTERIOR VIEW OF FAIRBANKS CO. WAREHOUSE, SHOWING STYLE OF CONSTRUCTION [137] REINFORCED CONCRETE DETAIL OF CORNER CONSTRUCTION IN THE REINFORCED CONCRETE WAREHOUSE ERECTED FOR THE FAIRBANKS CO. AT BALTIMORE, MD. 1381 MISCELLANEOUS ILLUSTRATIONS [I39l TEN-STORY REINFORCED CONCRETE BUILDING FOR BERNARD GLOEKLER & CO., PITTSBURG J BALLINGER & PERROT, ARCHITECTS CONCRETE RETAINING WALL ON LEXINGTON AVE., NEW YORK, SHOWING DETAILS OF CON- STRUCTION MISCELLANEOUS ILLUSTRATIONS MOLDING REINFORCED CONCRETE SLABS FOR THE ROOF OF THE CHITTENDEN POWER HOUSE, RUTLAND, VT. CONCRETE STEEL POWER HOUSE OF THE MANILA ELECTRIC RAILWAY AND LIGHT CO., MANILA, P. I. [HI] REINFORCED CONCRETE THE ROBERT GAIR FACTORY, BROOKLYN, N. Y., AN EXCELLENT EXAMPLE OF REINFORCED CONCRETE CONSTRUCTION. BUILT BY THE TURNER CONSTRUCTION CO., N. Y. [142] MISCELLANEOUS ILLUSTRATIONS BIRDSEYE VIEW OF THE PRELIMINARY ERECTION OF STEEL REINFORCEMENT FOR COLUMNS AND GIRDERS IN THE PUGH POWER BUILDING, CINCINNATI, OHIO. VIEW OF THE PUGH POWER BUILDING, SHOWING STRUCTURE FINISHED UP TO THE SIXTH FLOOR. THE DIMENSIONS OF THE BUILDING ARE 68 FEET FRONT, 335 FEET LENGTH AND TEN STORIES IN HEIGHT [143] REINFORCED CONCRETE VIEW OF PUGH POWER BUILDING, CINCINNATI, OHIO, SHOWING METHOD OF FORM CON- STRUCTION. THIS BUILDING IS AN EXCELLENT TYPE OF REINFORCED CONCRETE CONSTRUCTION. [144] MISCELLANEOUS ILLUSTRATIONS INTERIOR OF THE GOVERNMENT COAL POCKETS, BRADFORD, R. I. FORMS AND ELECTRICALLY- WELDED FABRIC REINFORCEMENT IN PLACE READY FOR THE CONCRETE FINISHED INTERIOR VIEW OF GOVERNMENT COAL POCKETS AT BRADFOBD, R. I, SHOWING CON- CRETE IN PLACE [145] REINFORCED CONCRETE GENERAL VIEW OF THE REINFORCED CONCRETE POWER HOUSE AND PULP MILL IN THE BED OF THE ANDROSCOGGIN RIVER AT BERLIN, N. H., INTERNATIONAL PAPER CO., OWNERS. THIS BUILDING WAS BUILT DURING A SEVERE NEW ENGLAND WINTER, SHOWING THE POSSIBILITY OF THE USE OF CONCRETE IN THE WINTER SEASON [I 4 6] MISCELLANEOUS ILLUSTRATIONS MISCELLANEOUS ILLUSTRATIONS THE MCNULTY BUILDING, 354~6 WEST 52ND ST., N. Y., BUILT OF REINFORCED CONCRETE BY TUCKER & VINTON, N. Y. UNDER SIDE OF TENTH FLOOR SETTLING. FORMS REMOVED. [I 4 8] MISCELLANEO US ILL USTRA TIONS VIEW OF THE CENTERING IN THE MCNULTY BUILDING, N. Y., WHICH SUPPORTS THE TENTH FLOOR WHILE THE CONCRETE IS SETTING [149] REINFORCED CONCRETE [ISO] MISCELLANEOUS ILLUSTRATIONS REINFORCED CONCRETE ADDITION TO THE E. R. THOMAS MOTOR CO/S PLANT AT BUFFALO KAHN SYSTEM USED THROUGHOUT INTERIOR VIEW OF E. R. THOMAS MOTOR CAR CO. PLANT, BUFFALO, N. Y. KAHN SYSTEM USED THROUGHOUT REINFORCED CONCRETE FRONT ELEVATION OF GARFORD CO. FACTORY, ELYRIA, OHIO, KAHN SYSTEM USED THROUGHOUT ONE OF FIVE BUILDINGS JUST COMPLETED FOR THE GLAZIER STOVE CO., CHELSEA, MICH. KAHN SYSTEM USED THROUGHOUT [152] UlSii'.msmr O2 CALIFORNI ; T BRARY This book is DUE on the last date stamped below. Fine schedule: 25 cents on first day overdue 50 cents on fourth day overdue One dollar on seventh day overdue. ENGINEERING LIEJRARY LD 21-100m-12,'46(A2012sl6)4120 ATI U.C. BERKELEY LIBRARIES 785318 ur Engineering , Library UNIVERSITY OF CALIFORNIA LIBRARY