GZ5.I3 C 7 Sere 1501 H COOPER GENERAL SPECIFICATIONS FOR STEEL HIGHWAY AND ELECTRIC RAILWAY BRIDGES Digitized by the Internet Archive in 2019 with funding from University of Illinois Urbana-Champaign Alternates https://archive.org/details/generalspecificaOOcoop “ The most perfect system of rules to insure success must be interpreted upon the broad grounds of professional mtelh- gence a,nd common sense. GENERAL SPECIFICATIONS FOR STEEL HIGHWAY AHD ELECTRIC RAILWAY BRIDGES AHD YIADDCTS. If NEW AND REVISED EDITION, 1901. '• -I ? K \ ■ ' ■ . h -i. ' ■ I V; 1 ■ ' • ; 91 By THEODORE COOPER : Consulting Engineer. ■ - ■ •" i?: framing sub JTabor. LIBRARY OF TH £ University of Illinois. f # CL Ay.S. BOOK. VOLUME. \ SrOV Accession No. § By THEODORE COOPER, M. Am. Soc. C. E. Specifications for Steel Railroad Bridges, 1901, . . $0 50 <( << (t << << u “ previous editions 25 Highway Bridges, I90 1 * • • 50 “ “ previous editions 25 American Railroad Bridges (reprint from Transac¬ tions of American Society of Civil Engineers, July, 1889), 60 pages, 8vo, cloth, . . . . 2 00 FOR SALE BY 220 Broadway, New York. I V V \ Gte. 13 % / / r& Copyright by Theodore Cooper Consulting Engineer, 35 Broadway, New York. General Specifications for Steel Highway and Electric Railway Bridges and Viaducts. FIFTH EDITION. 1901 . GENERAL DESCRIPTION. Bridges under these specifications are divided into six classes, classes, for different localities and various loadings, as fol¬ lows : (§ 38.) Class Ai. City bridges having buckle-plate floors and an accepted form of paving resting on a concrete base. (§ 29.) Class A2. City bridges having plank flooring. (§ 29.) Class B. Suburban bridges or Interurban bridges carry¬ ing heavy electric cars. (§ 29.) Class C. Town or country bridges carrying light elec¬ tric cars or bridges carrying heavy loads from quarries or manufactories. Class D. Country bridges carrying only ordinary high¬ way traffic. 2 Class Ei. Bridges carrying heaviest motor cars, only. Class E2. Bridges carrying light motor cars, only. i. All parts of the structures shall be of wrought steel, except the flooring, floor joists and wheel guards, when wooden floors are used. Cast-iron or cast-steel may be used in the machinery of movable bridges, for wheel guards, and in special cases for bed-plates. Kind of Girders. 2. The following kinds of girders shall preferably be employed : Spans, up to 25 feet_Rolled beams. “ 20 to 40 “ _Rolled beams or plate girders. “ 40 to 80 “ _Riveted plate or lattice girders. “ 80 to 120 “ _Lattice girders. “ over 120 “ _Lattice or pin-connected trusses. Length of span. In calculating strains the length of span shall be under¬ stood to be the distance between centres of end pins for trusses, c. to c. of trusses for cross floor beams, and be¬ tween centres of bearing plates for all longitudinal beams and girders. Trusses^ 3- Unless otherwise specified, the form of bridge trusses may be selected by the bidder ; for through bridges, the end vertical suspenders and two panels of the lower chord, at each end, will be made rigid members. In through bridges, the floor beams shall be riveted to the posts, above or below the pins. Lateral Bracing. 4- All lateral, sway and portal bracing must be made of shapes capable of resisting compression as well as tension, and must have riveted connections. All bridges must have lateral struts at the ends, except where end floor beams act as such. Trestle Towers. 5. Each trestle bent shall, as a general rule, be composed of two supporting columns, and the bents united in pairs to form towers; each tower thus formed of four columns shall ♦ be thoroughly braced in both directions, and have struts between the feet of the columns. The feet of the columns <"iv I Eu* 29 0 '01 McCHitrg. 4 0 3 must be secured to an anchorage capable of resisting double the specified wind forces. (§ 40.) 6. Each tower shall have sufficient base, longitudinally, to be stable when standing alone, without other support than its anchorage. (§§ 40, 43.) 7. Tower spans for high trestles shall not be less than 30 feet. 8. Where footwalks are required, they will generally be Foot-walks, placed outside of the trusses and supported on longitudinal beams resting on overhanging steel brackets. 9. A strong and suitable handrailing will be placed at Railing, each side of the bridge and be rigidly attached to the su¬ perstructure. 10. For all through bridges there shall be a clear head- Head-room, room of 15 feet above the floor, for Classes A, B, C and E; and a minimum head-room of 12^3 feet for Class D. 11. In comparing different proposals, the relative cost of Proposals, the required masonry or changes in existing work will be taken into consideration. 12. Contractors in submitting proposals shall furnish complete strain sheets, general plans of the proposed structures, and such detail drawings as will clearly show the dimensions of all the parts, modes of construction and the sectional areas. 13. Upon the acceptance of the proposal and the execu¬ tion of contract, all working drawings required by the En¬ gineer must be furnished free of cost. 14. No work shall be commenced or materials ordered Approval of . . Plans. until the working drawings are approved by the Engineer in writing; if such working drawings are detained more than one week for examination, the Contractor will be allowed an equivalent extension of time. FLOOR SYSTEM. 15. All cross floor beams will be rolled or riveted steel Floor Girders, girders, rigidly connected to the trusses at the panel points. 16. All longitudinal girders of bridges of Classes Ai and 4 A2 will be of steel; all track stringers of bridges of Classes B, C and E will be of steel. Unless otherwise specified all other longitudinal girders of Classes B and C will be of steel. The longitudinal girders of bridges of Class D may be either of wood or steel. When the longitudinal beams are of steel, they must be securely fastened to the cross floor beams. Country Bridges. wooden Floor, 17. Wooden floor joists will be spaced not over 2 feet centres, and will lap by each other, so as to have a full bearing on the floor beams, and will be separated -J inch for free circulation of air. Their scantling will vary in ac¬ cordance with the length of panels selected, but shall never be less than 3 inches, or one-fourth of depth in width. When spaced not over 2-foot centres, one joist shall be considered as carrying only two-thirds of the concentrated live load. 18. The floor plank shall be..inches thick, laid with |-inch openings, and spiked to each supporting joist. When this is to be covered with an additional wearing floor (§ 19), it must be laid diagonally and with -J inch openings; all plank shall be laid with the heart side down. The floor plank must have a thickness, in inches , at least equal to the distance apart of these beams, in feet , with a minimum thickness of 2\ inches. The floor plank must bear firmly upon the beams and be securely fastened to the same. 19. Where specified an additional wearing floor ij inches thick of white oak plank shall be placed over the above. (§ is.) Allowed strain on Timber. 20. The footwalk plank will be 2 inches thick and not over 6 inches wide, spaced with a inch openings. 21. There will be a wheel guard, of a scantling not less than 6x4, on each side of the roadway to prevent the hubs of wheels striking any part of the bridge. It should be blocked up from the floor to admit drainage and ventilation. 22. The maximum strain allowed upon the extreme fibre of the joist will be 1,200 pounds per square inch on yellow * 5 pine and white oak, and 1,000 pounds per square inch on white pine and spruce. City Bridges. 23. Buckle-plates will be not less than T 5 g- inch thick and Buckie piates. will crown 2 inches at the centre. Plates of this thickness and crown may be used to widths of 4 feet under the road¬ way and 5 feet under the footwalks. (§§ 93-96.) 24. Bridges with buckle plate floors will have a suitable Curbs and 0 . 1 . Guards. metal curb on each side of the roadway to hold paving and act as a wheel guard. The wheel guard must be so ar¬ ranged that it can be removed and replaced when worn or injured. There will also be a metal edging strip on each side of the footwalks to hold the paving in place. 25. The concrete over buckle-plates shall be at least 3 Concrete, inches thick on the roadway and 2 inches thick on the side¬ walks, over the highest point to be covered, not counting rivet heads. 26. The sidewalks shall slope 1 inch in 5 feet, preferably towards the roadway. The roadway shall crown from curb to centre 1 inch for each 10 feet of the roadway width. The depth of the curb will be 6 inches. 27. The subgrade, top of concrete, for the sidewalks will be_inches below final grade and slope. The concrete over roadway will be laid to the correct crowning and elevation to allow.inches for the selected paving. 28. Scuppers must be provided at frequent intervals along Scuppers, the curbs or wheel guards for drainage and for passing the sweepings and snow, clear from contact with any parts of the tracks or floor system. 29. Classes A and B shall be designed to carry at any Double Track, future time a double-track electric railway. Electric Railway Bridges. 30. The wooden floors will consist of transverse ties or wooden Floor, floor timbers; their scantling will vary in accordance with 6 the design of the supporting steel floor. (§ 22.) They shall be spaced with openings not exceeding six inches, and shall be notched down y 2 inch and be secured to the supporting girders by f-inch bolts at distances not over six feet apart. For deck bridges the ties will extend the full width of the bridge, and for through bridges at least every other tie shall extend the full width of bridge fora footwalk. Guard Timbers. 31. There shall be a guard timber (scantling not less than 5 x 7") on each side of each track, with its inner face parallel to and at_feet.inches from centre of track. Guard timbers must be notched one inch over every floor timber, and be spliced over a floor timber with a half and-half joint of six inches lap. Each guard timber shall be fastened to every third floor timber and at each splice with a three- quarter (|) inch bolt. All heads or nuts on upper faces of ties or guards must be countersunk below the surface of the wood. (§ 76.) 32. The guard and floor timbers must be continuous over all piers and abutments. 33. The floor timbers from centre to each end of span must be notched down over the longitudinal girders so as to reduce the camber in the track, as directed by the Engineer. 34. All the floor timbers shall have a full and even bearing upon the stringers ; no open joints or shims will be allowed. 35. On curves the outer rail must be elevated, as may be directed by the Engineer. cieat width. 36. In all through bridges the clear width from the centre of the track to any part of the trusses shall not be less than seven (7) feet at a height exceeding one foot above the rails where the tracks are straight, and an equivalent clearance, where the tracks are curved. 37. The standard distance, centre to centre of tracks on straight lines, will_feet. LOADS. 38. All the structures shall be proportioned to carry the following loads: 1 st. The weight of metal in the structure and floor. 7 ♦ 2d. The weight of the paving and concrete or the wooden floor, considering each foot of board measure to weigh 4J pounds for oak and other hard woods, and 31- pounds for spruce and white pine. These two items, taken together, shall constitute “ the Dead Load, dead load.” 3d. A “ live ” or moving load, according to one of the Live Loads, following classes: Class Ai and Class A2.—City Bridges : For the floor and its supports, on any part of the road¬ way or on each of the street car tracks, a concentrated load of 24 tons on two axles 10 feet centres (assumed to occupy 12 feet in width for a single line and 22 feet for a double line), and upon the remaining portion of the floor, including footwalks, a load of 100 pounds per square foot. For the trusses, loads as per Table A. Class B.—Suburban or Interurban Bridges: For the floor and its supports, on any part of the road¬ way, a concentrated load of 12 tons on two axles 10 feet centres or on each of the street car tracks a concentrated load of 24 tons on two axles 10 feet centres ; and upon the remaining portion of the floor, including footwalks, a load of 100 pounds per square foot of floor. For the trusses, loads as per Table A. Class C.—(Class B2 of former editions): For the floor and its supports, on any part of the road¬ way, a concentrated load of 12 tons on two axles 10 feet centres, or on street car track a concentrated load of 18 tons on two axles 10 feet centres ; and upon the remaining , portion of the floor, including footwalks, a load of 100 pounds per square foot of floor. For the trusses, loads as per Table A. Class D.—(Class C of former editions.) Country High¬ way Bridges : For the floor and its supports, a load of 80 pounds per square foot of total floor surface, or 6 tons on two axles 10 feet centres. For the trusses, loads as per Table A. 8 Class Ei.—Electric Railway Bridges, with Heavy Equip¬ ment : For the floor and its supports, a load of 24 tons on two axles 10 feet centres, on each track. For the trusses, loads as per Table A. Class E2.—Electric Railway Bridges, with Light Equip¬ ment : For the floor and its supports, a load of 18 tons on two axles 10 feet centres, on each track. For the trusses, loads as per Table A. TABLE A. —Live Loads for the Trusses. Class A. Span in feet. Pounds per lineal foot of each car track. Pounds per square foot of remaining floor surface. Up to 100. 1 800 100 105. 1 770 99 110. 1 740 98 115. 1 710 97 120. 1 680 96 125. 1 650 95 130. 1 620 94 135. 1 590 93 140. 1 560 92 145. 1 530 . 91 150. 1 500 90 155. 1 470 89 160. 1 440 88 165. 1 410 87 170. 1 380 86 175. 1 350 85 180. 1 320 84 185. 1 290 83 190. 1 260 82 195 . 1 230 81 200 and over... 1 200 80 Class B. Span in feet. Pounds per lineal foot of each car track. Pounds per square foot of remaining floor surface Up to 100. 1 800 80 105. 1 770 79 no-. 1 740 78 115. 1 710 77 120. 1 680 76 125. 1 650 75 130. 1 620 74 135. 1 590 73 140. 1 560 72 145. 1 530 71 150. 1 500 70 155 . 1 470 69 160. 1 440 68 165. 1 410 67 170. 1 380 66 175. 1 350 65 180. 1 320 64 185. 1 290 63 190. 1 280 62 195. 1 230 61 200 and over. 1 200 60 Class C. Up to 100. 1 200 80 105. 1 190 79 110. 1 180 78 115. 1 170 77 120. 1 160 76 125. 1 150 75 130. l 140 74 135. 1 130 73 140. l 120 72 145. 1 110 71 150. 1 100 70 155. 1 090 69 160. 1 080 68 165. 1 070 67 170. 1 060 66 175. 1 050 65 180. 1 040 64 185. 1 030 63 190. 1 020 62 195. 1 010 61 200 and over. 1 000 60 9 TABLE A ( Continued ) —Live Loads for the Trusses. Class D. Class E 1. Class E 2. Span in feet. Pounds per square foot of floor surface. Span in feet. Pounds per lineal foot of each car track. Span in feet. Pounds per lineal foot of each car track. Up to Up to Up to 75. 80 100. 1 800 100.;*.. 1 200 80. 79 105. 1 770 105. 1 190 85. 78 110. 1 740 110. 1 180 90. 77 115. 1 710 115. 1 170 95. 76 120. 1 680 120. 1 160 100. 75 125. 1 650 125. 1 150 105. 74 130. 1 620 130. 1 140 110. 73 135. 1 590 135. 1 130 115. 72 140. 1 560 140. 1 120 120. 71 145. 1 530 145. 1 110 125. 70 150. 1 500 150. 1 100 130. 69 155. 1 470 155. 1 090 135. 68 160. 1 440 160. 1 080 140.,. 67 165. 1 410 165. 1 070 145. 66 170. 1 380 170. 1 060 150. 65 175. 1 350 175. 1 050 155. 64 180. 1 320 180. 1 040 160. 63 185. 1 290 185....:..:::: 1 030 165. 62 190. 1 260 190. 1 020 170. 61 195. 1 230 195. 1 010 175. 60 200 and over. 1 200 200 and over. 1 000 180. 59 185. 58 190. 57 195. 56 200 and over. 55 1 The maximum strains due to all positions of either of the above “ live loads,” of the required class, and of the “ dead loads,” shall be taken to proportion all the parts of the structure. 39. To provide for wind strains and vibrations, the top wind Bracing lateral bracing in deck bridges, and the bottom lateral brac¬ ing in through bridges, shall be proportioned to resist a lateral force of 300 pounds for each foot of the span ; 150 pounds of this to be treated as a moving load. The bottom lateral bracing in deck bridges, and the top lateral bracing in through bridges, shall be proportioned to resist a lateral force of 150 pounds for each lineal foot. For spans exceeding 300 feet, add in each of the above cases 10 pounds additional for each additional 30 feet. 40. In trestle towers the bracing and columns shall be proportioned to resist the following lateral forces, in addition to the strains from dead and live loads: 10 The trusses loaded or unloaded, the lateral pressures specified above ; and a lateral pressure of ioo pounds for each vertical lineal foot of the trestle bents. Temperature. 41. Variation in tem peratu re, to the extent of i5odegrees, shall be provided for. centrifugal 42. For electric railways on curves, the additional effects due to the centrifugal force of cars single or coupled shall be considered as a live load. It will be assumed to act 5 feet above base of rail, and will be computed for a speed of 40 miles per hour. Longitudinal 43. The strains produced in the bracing of the trestle towers, in any members of the trusses, or in the attach¬ ments of the girders or trusses to their bearings, by sud¬ denly stopping the maximum electric car trains on any part of the work must be provided for; the coefficient of friction of the wheels on the rails being assumed as 0.20. 44. All parts shall be so designed that the strains coming upon them can be accurately calculated. PROPORTION OF PARTS. Tensile Strain. 45. All parts of the structures shall be proportioned in tension by the following allowed unit strains: Medium Steel. For Medium Steel. Pounds per square inch. Floor beam hangers, and other similar members liable to sudden loading, net section.. 8,000 Longitudinal, lateral and sway bracing, for wind and live load strains (§§ 6, 39, 40)_ 18,000 Solid rolled beams, used as cross floor beams and stringers__ 13,000 Bottom flanges of riveted girders, net section_ 13,000 Bottom chords, main diagonals, counters live^ioads. dead°ioads. and long verticals.. 12,500 25,000 For swing bridges and other movable structures, the dead load unit strains, during motion, must not exceed three- fourths of the above allowed unit strains for dead load on stationary structures. Soft steel. Soft Steel may be used in tension with unit strains ten per cent, less than those allowed for Medium Steel. 11 46. Angles subject to direct tension must be connected by both legs, or the section of one leg only will be con¬ sidered as effective. 47. In members subject to tensile strains full allowance Net section, shall be made for reduction of section by rivet-holes, screw- threads, etc. (§§ 75, 79.) 48. Compression members shall be proportioned by the c^P r s essive following allowed unit strains: For Medium Steel . I Medium Steel. Chord segments P= 12,000—55—for live load strains. r P== 24,000—1 io—for dead load strains. r All posts of ^ through P=\o,ooo —45—for live load strains, bridges. r P=2o,000 —90—for dead load strains. r All posts of 1 deck bridges ^=11,000—40—for live load strains, and trestles. r P=2 2,000—80—for dead load strains. r End posts are not to be considered chord segments. Lateral struts j and rigid P= 13,000—60—for wind strains; bracing. r for live load strains use two-thirds of the above. (§§ 42, 43, 124.) ____ _ .. P=the allowed strain in compression per square inch of cross-section, in pounds. /=the length of compression member, in inches, c. to c., of connections. r=the least radius of gyration of the section, in inches. No compression member, however, shall have a length 12 exceeding ioo times its least radius of gyration for main members, or 120 times for laterals. For swing bridges and other movable structures, the dead load unit strains during motion must not exceed £ of the above allowed unit strains for dead load on stationary structures. 49. For long span bridges, when the ratio of the length and width of span is such that it makes the top chords acting as a whole, a longer column than the segments of the chord, the chord will be proportioned for this greater length. soft steei. Soft Steel may be used in compression with unit strains fifteen per cent, less than those allowed for Medium Steel. 50. The areas obtained by dividing the live load strains by the live load unit strains will be added algebraically to the areas obtained by dividing the dead load strains by the dead load unit strains to determine the required sectional area of any member. (§ 62.) Alternate 51. All members and their connections subject to alter- nate strains 01 tension and compression shall be propor¬ tioned to resist each kind of strain. Both of the strains shall, however, be considered as increased by an amount equal to t 8 o of the least of the two strains, for determining the sec¬ tional areas by the above-allowed unit strains. (§§45,48.) Effect of wind 52. The strains in the truss members or trestle posts on Chord , . . ^ strains. from the assumed wind forces need not be considered ex¬ cept as follows: ist. When the wind strains on any member exceed 25 per cent, of the maximum strains due to the dead and live loads upon the same member. The section shall then be increased until the total strain per square inch will not exceed by more than 25 per cent, the maximum fixed for dead and live loads only. 2d. When the wind strain alone or in combination with a possible temperature strain, can neutralize or reverse the strains in any member. Rivets, Bolts 53. The rivets in all members, other than those of the and Pins. n floor and lateral systems, must be so spaced that the shear¬ ing strain per square inch shall not exceed 10,000 pounds; 13 nor the pressure on the bearing surface (diameter X thick¬ ness of the piece) of the rivet-hole exceed 18,000 pounds per square inch. The rivets in all members of the floor system, including all hanger connections, must be so spaced that the shearing strains and bearing pressures shall not exceed 80 per cent, of the above limits. The rivets in the lateral and sway bracing will be allowed 40 per cent, increase upon the above limits. In the case of field riveting (and for bolts as per § 76) the above-allowed shearing strains and pressures shall be re¬ duced one-third. Rivets and bolts must not be used in direct tension. 54. Pins shall be proportioned so that the shearing strain shall not exceed 10,000 pounds per square inch ; nor the pressure on the bearing surface of any member (other than forged eye-bars, see § 104) connected to the pin be greater per square inch than 18,000 pounds ; nor the bending strain exceed 20,000 pounds, when the applied forces are consid¬ ered as uniformly distributed over the middle half of the bearing of each member. 55. When any member is subjected to the action of both combined axial and bending strains, as in the case of end posts 0 f stra,ns ' through bridges (§ 52), or of chords carrying distributed floor loads, it must be proportioned so that the greatest fibre strain will not exceed the allowed limits of tension or compression on that member. If the fibre strain resulting from the weight only, of any member, exceeds ten per cent, of the allowed unit strain on such member, such excess must be considered in propor¬ tioning the areas. 56. In beams and plate girders the compression flanges Compression shall be made of same section as the tension flanges. 57. Riveted longitudinal girders shall have, preferably, a Depth of depth not less than ^ of the span. Rolled beams used as longitudinal girders shall have, preferably, a depth not less than of the span. 58. Plate girders shall be proportioned upon the supposi- Plate Girders 14 tion that the bending or chord strains are resisted entirely by the upper and lower flanges, and that the shearing or web strains are resisted entirely by the web-plate ; no part of the web-plate shall be estimated as flange area. The distance between centres of gravity of the flange areas will be considered as the effective depth of all girders, web piates. 59. The webs of plate girders must be stiffened at inter¬ vals, not exceeding the depth of the girders or a maximum of 5 feet, wherever the shearing strain per square inch ex¬ ceeds the strain allowed by the following formula : Allowed shearing strain = 12,500 — 9 oH, where H = ratio of depth of web to its thickness ; but no web-plates shall be less than t 5 q of an inch in thickness. Stiffeners. 60. All stiffeners must be capable of carrying the maximum vertical shear without exceeding the allowed unit strain. P= 12,000 — 55-. r Each stiffener must connect to the webs by enough rivets to transfer the maximum shear to or from the webs (§ 83). Rolled Beams. 61. Rolled beams shall be proportioned (§§ 45, 48) by their moments of inertia. Counters. 62. The areas of counters shall be determined by taking the difference in areas due to the live and dead load strains considered separately (§ 45, 105). 63. For bridges carrying electric or motor cars counters shall be provided and proportioned, so that a future increase of 25 per cent, in the specified live load shall notin any case increase the allowed unit strain more than 25 per cent. DETAILS OF CONSTRUCTION. Details. 64. All the connections and details of the several parts of the structures shall be of such strength that, upon testing, rupture will occur in the body of the members rather than in any of their details or connections. 65. Preference will be had for such details as shall be most accessible for inspection, cleaning and painting ; no closed sections will be allowed. Riveting. 66. The pitch of rivets in all classes of work shall never * 15 exceed 6 inches, or sixteen times the thinnest outside plate, nor be less than three diameters of the rivet. 67. The rivets used shall generally be f and | inch diameter. 68. The distance between the edge of any piece and the centre of a rivet-hole must never be less than iy inches, except for bars less than 2-§ inches wide ; when practicable it shall be at least two diameters of the rivet. 69. For punching, the diameter of the die shall in no case exceed the diameter of the punch by more than of an inch, and all holes must be clean cuts without torn or ragged edges. 70. All rivet holes must be so accurately spaced and punched that when the several parts forming one member are assembled together, a rivet y 1 ^ inch less in diameter than the hole can generally be entered, hot, into any hole, with¬ out reaming or straining the metal by “ drifts occasional variations must be corrected by reaming. 71. The rivets when driven must completely fill the holes. The rivet-heads must be round and of a uniform size for the same sized rivets throughout the work. They must be full and neatly made, and be concentric to the rivet-hole, and thoroughly pinch the connected pieces together. 72. Wherever possible, all rivets must be machine driven. The machines must be capable of retaining the applied pressure after the upsetting is completed. No hand-driven rivets exceeding $ inch diameter will be allowed. 73. Field riveting must be reduced to a minimum or entirely avoided, where possible. 74. All holes for field rivets, except those in connections of the lateral and sway systems, shall be accurately drilled or reamed to an iron template or be reamed true while the parts are temporarily connected together. 75. The effective diameter of a driven rivet will be as- Net Sections, sumed the same as its diameter before driving. In deduct¬ ing the rivet-holes to obtain net sections in tension mem¬ bers, the diameter of the rivet-holes will be assumed as •§■ inch larger than the undriven rivets. The rupture of a riveted tension member is to be con- 16 Bolts. Splices. Abutting Joints. Web Splices. Stiffeners. sidered as equally probable, either through a transverse line of rivet-holes or through a diagonal line of rivet-holes, where the net section does not exceed by 30 per cent, the net section along the transverse line. The number of rivet-holes to be deducted for net section will be determined by this condition. (§§ 47-79.) 76. When members are connected by bolts the holes must be reamed parallel and the bolts turned to a driving fit. All bolts must be of neat lengths, and shall have a washer under the heads and nuts where in contact with wood. Bolts must not be used in place of rivets, except by special permission. 77. All nuts must be of hexagonal shape. 78. All joints in riveted tension members must be fully and symmetrically spliced. 79. Riveted tension members shall have an effective sec¬ tion through the pin-holes 25 per cent, in excess of the net section of the member, and back of the pin at least 75 per cent, of the net section through the pin-hole. 80. In continuous compression members, as chords and trestle posts, the abutting joints with planed laces must be placed as close to the panel points as is practicable, and the joints must be spliced on all sides with at least two rows of closely pitched rivets on each side of the joint. Joints in long posts must be fully spliced. 81. In compression members, abutting joints with un¬ tooled faces must be fully spliced, as no reliance will be placed on such abutting joints. The abutting ends must, however, be dressed straight and true, so there will be no open joints. 82. The webs of plate girders must be spliced at all joints by a plate on each side of the web. 83. All web-plates must have stiffeners over bearing points and at points of local concentrated loadings; such stiffeners must be fitted at their ends to the flange angles, at the bearing points. (§§ 59-60.) 84. All other angles, filling and splice plates on the webs of girders and riveted members must fit at their ends to 17 the flange angles, sufficiently close to be sealed, when painted, against admission of water. 85. Web-plates of all girders must be arranged so as not w e b Plates, to project beyond the faces of the flange angles, nor on the top be more than T ^- inch below the face of these angles, at any point. 86. Wherever there is a tendency for water to collect, the spaces must be filled with a suitable waterproof material. 87. In girders with flange plates, at least one-half of the Flange Plates, flange section shall be angles or else the largest sized angles must be used. Flange plates must extend beyond their theoretical length, two rows of rivets at each end. 88. The flange plates of all girders must be limited in width so as not to extend beyond the outer lines of rivets connecting them with the angles, more than five inches or more than eight times the thickness of the first plate. Where two or more plates are used on the flanges, they shall either be of equal thickness or shall decrease in thickness outward from the angles. 89. The compression flanges of beams and girders shall be Compression stayed against transverse crippling when their length is more than sixteen times their width. 90. The unsupported width (distance between rivets) of width oi plates, plates subject to compression shall not exceed thirty times their thickness; except cover plates of top chords and end posts, which will preferably be limited to forty times their thickness ; where a greater relative width is used in chords and end posts, however, only forty times the thickness shall be considered as effective section. 91. In lattice girders and trusses the web members must be double and connect symmetrically to the webs of the chords. The use of plates or flats, alone, for tension mem¬ bers must be avoided, where it is possible; in lattice trusses, the counters, suspenders and two panels of the lower chord, at each end, must be latticed; all other ten¬ sion members must be connected by batten plates or latticed. (§ hi.) 92. Where the floor timbers are supported at their ends 18 on the flange of one angle, such angle must have two rows ol rivets in its vertical leg, spaced not over 4 inches apart. Buckie Plates. 93. Buckle plates must be firmly riveted to the support¬ ing beams and be spliced at all free edges. Preferably they will be made in continuous sheets of panel lengths. They may be pressed or formed without heating. (§ 23.) 94. A buckle-plate floor, as specified, may be considered as the required lateral system of bracing at the floor level. 95. The buckle-plates of the sidewalks will be covered to the proper slope and level for the wearing pavement with bitumen concrete of an accepted and waterproof character. 96. The buckle-plates of the roadway will be covered with an acceptable and waterproof concrete (bitumen or cement) to the proper crown and grade for the wearing pavement, but at no place must the concrete be less than 3 inches thick. Thickness of 97- For main members and their connections no material shall be used of a less thickness than T 5 ^ of an inch ; and for laterals and their connections, no material less than J of an inch in thickness ; except for lining or filling vacant spaces. No bars shall be used with a less net area than f of one square inch. Eye Bars 98. The heads of eye-bars shall be so proportioned and made, that the bars will preferably break in the body of the original bar rather than at any part of the head or neck. The form of the head and the mode of manufacture shall be subject to the approval of the Engineer. (§§ 138, 139, 159, 160.) 99. The bars must be free from flaws and of full thick¬ ness in the necks. They shall be perfectly straight before boring. The holes shall be in the centre of the head, and on the centre line of the bar. 100. The bars must be bored to lengths not varying from the calculated lengths more than -g 1 ^ of an inch for each 25 feet of total length. 101. Bars which are to be placed side by side in the structure shall be bored at the same temperature and of such equal length that upon being piled on each other the 19 pins shall pass through the holes at both ends without driving. 102. The lower chord shall be packed as narrow as possi¬ ble. 103. The pins shall be turned straight and smooth; chord p; ns . pins shall fit the pin-holes within ^ of an inch, for pins less than 4-J inches diameter; for pins of a larger diameter the clearance may be inch. 104. The diameter of the pin shall not be less than three- quarters the largest dimension of any eye-bar attached to it. The several members attaching to the pin shall be so packed as to produce the least bending moment upon the pin, and all vacant spaces must be filled with wrought fill¬ ing rings. 105. All bars with screw ends shall be upset at the ends, Upset Ends, so that the diameter at the bottom of the threads shall be -Jg- inch larger than any part of the body of the bar. Where closed sleeve nuts are used on adjustable members the effective length of thread shall be legibly stamped at the screw ends of each bar. Adjustable counters to be avoided where practicable. 106. All threads must be of the United States standard, except at the ends of the pins. 107. Floor beam hangers when permitted shall be made Hangers, without adjustment and so placed that they can be readily examined at all times. (§ 3.) 108. All the floor beams must be effectually stayed against end motion or any tendency to rotate from the action of the lateral system. ioq. Compression members shall be of steel, and of ap- Compression Members. proved forms. no. The pitch of rivets at the ends of compression mem¬ bers shall not exceed four diameters of the rivets for a length equal to twice the width of the member. hi. The open sides of all compression members shall be stayed by batten plates at the ends and diagonal lattice- work at intermediate points. The batten plates must be placed as near the ends as practicable, and shall have a 20 length not less than the greatest width of the member or i \ times its least width. The size and spacing of the lattice bars shall be duly proportioned to the size of the member. They must not be less in width than i-J inches for mem¬ bers 6 inches jin width, if inches for members 9 inches in width, 2 inches for members 12 inches in width, nor 21- inches for members 15 inches in width, nor 2 \ inches for members 18 inches and over in width. Single lattice bars shall have a thickness not less than ^ or double lattice bars connected by a rivet at the intersection, not less than of the distance between the rivets connecting them to the members. They shall be inclined at an angle not less than 6o° to the axis of the member for single latticing, nor less than 45 0 for double latticing with riveted intersections. The pitch of the latticing must not exceed the width of the channel plus nine inches. 112. Where necessary, pin-holes shall be reinforced by plates, some of which must be of the full width of the member, so the allowed pressure on the pins shall not be exceeded, and so the strains shall be properly distributed over the full cross-section of the members. These reinforc¬ ing plates must contain enough rivets to transfer their pro¬ portion of the bearing pressure, and at least one plate on each side shall extend not less than six inches beyond the edge of the batten plates. (§ 111.) 113. Where the ends of compression members are forked to connect to the pins, the aggregate compressive strength of these forked ends must equal the compressive strength of the body of the members. 114. In compression chord sections and end posts, the material must mostly be concentrated at the sides, in the angles and vertical webs. Not more than one plate, and this not exceeding § inch in thickness, shall be used as a cover plate, except when necessary to resist bending strains, or to comply with § 90. (§55.) 115. The ends of all square-ended members shall be planed smooth, and exactly square to the centre line of strain. 21 116. The ends of all floor beams and stringers shall be Floor Beams faced true and square, and to correct lengths. Allowance and Strmgers must be made in the thickness of the end angles to provide for such facing without reducing the required effective strength of such end angles. 117. All members must be free from twists or bends. Por¬ tions exposed to view shall be neatly finished. 118. Pin-holes shall be bored exactly perpendicular to aPin-Hoies. vertical plane passing through the centre line of each mem¬ ber, when placed in a position similar to that it is to occupy in the finished structure. 119. The several pieces forming one built member must fit closely together, and when riveted shall be free from twists, bends or open joints. 120. All through bridges shall have latticed portals, of Transverse approved design, at each end of the span, connected rigidly Bracing to the end posts and top chords. They shall be as deep as the specified head-room will allow, and provision shall be made in the end posts for the bending strains from wind pressure. (§§ 4, 10, 39, 52.) 121. When the height of the trusses exceeds 20 feet, an approved system of overhead diagonal bracings shall be attached to each post and to the top lateral struts. 122. Knee braces shall be placed at each intermediate panel point, and connected to the vertical posts and top lateral struts, for trusses 20 feet and less in depth. 123. Pony trusses and through plate or lattice girders shall be stayed by knee braces or gusset plates attached to the top chords at the ends and at intermediate points, and attached below to the cross floor beams or to the transverse struts. 124. All deck girders shall have transverse braces at the ends. All deck bridges shall have transverse bracing at each panel point. This bracing shall be proportioned to resist the unequal loading of the trusses. 12$. All members of the web, lateral, longitudinal or sway systems must be securely riveted at their intersections to prevent sagging and rattling. 22 Bed Plates. 12 6. All bed-plates must be of such dimensions that the greatest pressure upon the pedestal stone shall not exceed 250 pounds per square inch. Friction 127. All bridges over 8o feet span shall have hinged RoUers.bolsters on both ends, and at one end nests of turned fric¬ tion rollers running between planed surfaces. These rollers shall not be less than 2-J inches diameter for spans ioo feet or less, and for greater spans this diameter shall be increased in proportion of i inch for ioo feet additional. The rollers shall be so proportioned that the pressure per lineal inch of roller shall not exceed the product of the diameter in inches by 300 pounds (30od.). The rollers must be of machinery steel and the bearing plates of medium steel. The rollers and bearings must be so arranged that they can be readily cleaned and so that they will not hold water. 128. Bridges less than 80 feet span shall be secured at one end to the masonry, and the other end shall be free to move longitudinally upon smooth surfaces. 129. Where two spans rest upon the same masonry, a con¬ tinuous plate, not less than f inch thick, shall extend under the two adjacent bearings, or the two bearings must be rigidly tied together. Pedestals and 130. Pedestals shall be made of riveted plates and angles. Bed-Plates. • • All bearing surfaces of the base plates and vertical webs must be planed. The vertical webs must be secured to the base by angles having two rows of rivets in the vertical legs. No base plate or web connecting angle shall be less in thickness than \ inch. The vertical webs shall be of sufficient height and must contain material and rivets enough to practically distribute the loads over the bearings or rollers. Where the size of the pedestal permits, the vertical webs must be rigidly connected transversely. 131. All the bed-plates and bearings under fixed and movable ends must be fox-bolted to the masonry; for trusses, these bolts must not be less than inches diameter; for plate and other girders, not less than | inch diameter. 23 The contractor must furnish all bolts, drill all holes and set bolts to place with sulphur or Portland cement. 132. While the expansion ends of all trusses must be free to move longitudinally under changes of temperature, they shall be anchored against lifting or moving sideways. 133. All bridges shall be cambered by giving the panels Camber, of the top chord an excess of length in the proportion of of an inch to every ten feet. 134. The lower struts in trestle towers must be capable Trestle Towers, of resisting the strains due to changes of temperature or of moving the tower pedestals under the effects of expansion or contraction. For high or massive towers, these lower struts will be securely anchored to intermediate masonry piers, or the tower pedestals will have suitably placed friction rollers, as may be directed by the Engineer. 135. All joints in the tower columns shall be fully spliced for all possible tension strains, and to hold the parts firmly in position. (§ 80.) 136. Tower footings and bed-plates must be planed on all bearing surfaces; and the holes for anchor bolts slotted to allow for the proper amount of movement. (§ 41.) 137. All workmanship shall be first-class in every par- Workmanship, ticular. 138. All eye-bars must be made of medium steel. Eye-Bars. 139. Eye-bars, all forgings and any pieces which have been partially heated or bent cold must be wholly an¬ nealed. Crimped stiffeners need not be annealed. 140. No reliance will be placed upon the welding of steel. 141. No sharp or unfilleted angles or corners will be allowed in any piece of metal. 142. Medium steel maybe used in compression in chords, Medium steel, posts and pedestals without reaming of punched holes, for all thicknesses of metal, which will stand the drifting test § 154); provided all sheared edges are planed off to a depth of -J inch. In all other cases medium steel over f inch thick must 24 Soft Steel, Pilot Nuts have all sheared edges planed off to a depth of | inch and all holes drilled or reamed to a diameter £ inch larger than the punched holes, so as to remove all the sheared surface of the metal. 143. Soft steel need not be reamed if it satisfies the drift- ing test (§§ 154, 155). 144. All parts of any tension or compression flange or member, must be of the same kind of steel, but webs of plate girders and the tension members of all girders, plate or lattice, may be made of soft steel in connection with compression members of medium steel. 145. All splices must be of the same kind of steel as the parts to be joined. 146. Pilot nuts must be used during the erection to pro¬ tect the threads of the pins. * QUALITY OF MATERIAL. Steel. 147. All steel must be made by the Open Hearth process. The phosphorus must not exceed 0.06 of one per cent, for steel made by the acid method, or 0.04 for steel by the basic method. 148. The steel must be uniform in character for each specified kind. The finished bars, plates and shapes must be free from cracks on the faces or corners, and have a clean, smooth finish. No work shall be put upon any steel at or near the blue temperature or between that of boiling water and of ignition of hard wood sawdust. 149. The tensile strength, elastic limit* and ductility shall be determined by samples cut from the finished material after rolling. The samples to be at least 12 inches long, and to have a uniform sectional area not less than J square inch. * For the purpose of these specifications, the Elastic Limit will be considered the least strain producing a visible permanent elongation in a length of 8 inches, as shown by scribe marks of a pair of finely pointed dividers. If the yield point or drop of the beam can be calibrated for any machine and its speed to represent the elastic limit within 5 percent., it may be used for general cases. Test reports must state by which method the elastic limit was determined. 25 150. Material which is to be used without annealing or further treatment is to be tested in the condition in which it comes from the rolls. When material is to be annealed or otherwise treated before use, the specimen representing such material is to be similarly treated before testing, for tensile strength. The elongation shall be measured on an original length of 8 inches. Two test pieces shall be taken from each melt or blow of finished material, one for tension and one for bend¬ ing. (Art. 166.) 151. All samples or full-sized pieces must show uniform fine grained fractures of a blue steel-gray color, entirely free from fiery lustre or a blackish cast. 152. Medium Steel shall have an ultimate strength, when Medium Steel, tested in samples of the dimensions above stated, of 60,000 to 68,000 pounds per square inch, an elastic limit of not less than one-half of the ultimate strength, and a minimum elongation of 22 per cent, in 8 inches. Steel for pins may have a minimum elongation of 15 per cent. 153. Before or after heating to a low cherry red and cooling in water at 82 degrees Fahr., this steel must stand bending to a curve whose inner radius is one and a half times the thickness of the sample, without cracking. 154. For all medium steel, § inch or less in thickness, rivet holes punched as in ordinary practice (§§ 68, 69, 70), must stand drifting to a diameter one-third greater than the original holes, without cracking either in the periphery of the holes or on the external edges of the piece, whether they be sheared or rolled. 155. Soft Steel Shall have an ultimate strength, on same soft steel, sized samples, of 54,000 to 62,000 pounds per square inch, an elastic limit not less than one-half the ultimate strength, and a minimum elongation of 25 per cent, in 8 inches. For soft steel the above drifting test (§ 154) shall apply to all material to be riveted. 156. Before or after heating to a light yellow heat and quenching in cold water, this steel must stand bending 180 «s 26 Rivet Steel. Eye Bars, Pins. Steel Castings. degrees, to a curve whose inner radius is equal to the thickness of the sample, without sign of fracture. 157. Rivet Steel shall have an ultimate strength of 50,000 to 58,000 pounds per square inch, an elastic limit not less than one-half the ultimate strength and an elongation of 26 per cent. 158. The steel for rivets must, under the above bending test (156), stand closing solidly together without sign of fracture. 159. Eye-bar material, ij inches and less in thickness, shall, on test pieces cut from finished material, fill the above requirements. For thicknesses greater than i-J inches, there will be allowed a reduction in the percentage of elongation of 1 per cent, for each -§■ of an inch increase of thickness, to a minimum of 20 per cent. (Art. 138.) 160. Full sized eye-bars shall show not less than 10 per cent, elongation in the body of the bar, and an ultimate strength not less than 56,000 pounds per square inch. Should a bar break in the head, but develop 10 per cent, elongation and the ultimate strength specified, it shall not be cause for rejection, provided not more than one-third of the total number of bars tested break in the head. 161. Pins over 7 inches in diameter shall be forged. Blooms for pins shall have at least three times the sectional area of the finished pins. 162. A variation of cross-section or weight in the finished members of 2-J- per cent, from the specified size may be cause for rejection. Steel Castings. 163. Steel castings will be used for drawbridge wheels, track segments and gearing. (Art. 1.) They must be true to form and dimensions, of a work¬ manlike finish and free from injurious blowholes and defects. All castings must be annealed. When tested in specimens of uniform sectional area of at least -J square inch for a distance of 2 inches, they must 27 show an ultimate strength of not less than 67,000 pounds per square inch, an elastic limit of one-half the ultimate, and an elongation in 2 inches of not less than 10 per cent. The metal must be uniform in character, free from hard or soft spots, and be capable of being properly tool finished. Cast Iron. 164. Except where cast steel or chilled iron is required, Cast Iron, all castings must be of tough, gray iron, free from cold shuts or injurious blowholes, true to form and thickness, and of a workmanlike finish. Sample pieces, 1 inch square, cast from the same heat of metal in sand moulds, shall be capable of sustaining, on a clear span of 12 inches, a central load of 2,400 pounds, when tested in the rough bar. A blow from a hammer shall produce an indentation on a rectangu¬ lar edge of the casting without flaking the metal. Timber. 165. The timber, unless otherwise specified, shall be Timber, strictly first-class spruce, white pine, southern yellow pine or white oak bridge timber, sawed true, and out of wind, full size, free from wind shakes, large or loose knots* decayed or sap wood, worm holes, or other defects impair¬ ing its strength or durability. It will be subject to the inspection and acceptance of the Engineer. INSPECTION. 166. All facilities for inspection of the materials and Inspection, workmanship shall be furnished by the contractor. He shall furnish without charge such specimens (prepared) of the several kinds of steel to be used, as may be required to determine their character. 167. The contractor must furnish the use of a testing machine capable of testing the above specimens at all mills where the steel may be manufactured, free of cost. 168. Full sized parts of the structure may be tested at the option of the Engineer, but if tested to destruction, such material shall be paid for at cost, less its scrap value 28 to the contractor, if it proves satisfactory. If it does not stand the specified tests, it will be considered rejected material, and be solely at the cost of the contractor. PAINTING. Painting. 169. All metal work before leaving- the shop shall be thor¬ oughly cleaned from all loose scale and rust, and be given one good coating of pure raw linseed oil, well worked into all joints and open spaces. Buckle-plates shall be given a thick and thorough coat¬ ing of red lead and linseed oil betore shipment. All rivet heads in the buckle-plate floor shall also be coated with this read lead paint as soon as practicable after they are driven. 170. In riveted work the surfaces coming in contact shall each be painted before being riveted together. Bottoms of bed plates, bearing-plates, and any parts which are not accessible for painting after erection, shall have two coats of paint; the paint shall be a good quality of iron ore paint, mixed with pure linseed oil. 171. After the structure is erected, the metal work shall be thoroughly and evenly painted with two additional coats of paint, mixed with pure linseed oil. All recesses which will retain water, or through which water can enter, must be filled with thick paint or some waterproof cement before receiving the final painting. 172. Pins, bored pin-holes, screw threads and turned fric¬ tion rollers shall be coated with white lead and tallow before being shipped from the shop. ERECTION. Erection. 173* The contractor, unless it be otherwise specified, shall furnish all staging and false work, shall erect and adjust all the metal work, and put in place all floor timbers, guards, etc., complete. 174. The contractor shall so conduct all his operations as not to interfere with the work of other contractors, or close any thoroughfare by land or water, except by written con¬ sent of. 29 175 - The contractor shall assume all risks of accidents to men or material prior to the acceptance of the finished structure. The contractor must also remove all false work, piling and other obstructions, or unsightly material produced by his operations. FINAL TEST. 176. Before the final acceptance the Engineer may make Final Test, a thorough test by passing over each structure the specified loads, or their equivalent, or by resting the maximum load upon the structure for twelve hours. After such tests the structures must return to their orig¬ inal positions without showing any permanent change in any of their parts. EXPORT WORK. All plans, including working drawings, must be submitted Export work, for the examination and approval of the Consulting Engineer before the material is ordered or any work done. Any proposed modification of accepted plans, to adapt them to the plant and methods of the manufacturer or to facilitate the prompt delivery of the work, must also be submitted to and approved by the Consulting Engineer, before such changes can be allowed. In all designs, the length and size of parts must be so arranged that they can be readily handled and stored dur¬ ing transportation to the site. Length of bars, posts, chords and pieces of small section must not exceed.feet. Length of girders or girder sections over.feet in width must not exceed.feet. Weight of any single piece must not exceed. pounds. Pins, roller-nests, bolts, rivets and all small pieces must be packed in strong, iron-bound boxes, with the detailed contents of each box legibily marked on the outside. Boxes to be consecutively lettered or numbered. 30 The screw-ends of all bars to be securely protected by canvass wrapped and wired about the same. Every piece must not only be legibily marked by paint, but also by letters stamped on the metal, showing its loca¬ tion in the structure. All necessary rivets for the field connections, with an extra allowance of 25 per cent, for each kind, shall be sent with each shipment. The customary pilot-nuts (§ 146) for all pins shall be sent with the pins. SUPPLEMENTARY. The following special clauses shall apply in addition to previous general clauses, to the special work included in the attached contract: 31 GENERAL DATA. For a bridge crossing____in the town of.. .County of_State of ..to be built according to the general requirements of the accompanying specifications: Width of roadway..... Number of footwalks..... Width of footwalks____ Kind of floor or paving.... Number of car tracks. Spacing “ “ ... Height of.floor above flood line_ Height of floor above ordinary stage of water.. Depth of river at ordinary stage of water.... Character of river bed___ Usual seasons for floods__ __ Length of haul from nearest freight station__ Specified live load, Class Ai, A2, B, C, D, Ei or E2, para¬ graph 38, to be adopted for this bridge_ Sizes of piers (if built or contracted for)..... Skew of piers, or angle of current with line of the bridge. Total length of bridge_______ Length of spans centre to centre of piers.. .. APPENDIX. 34 TABLE I. Maximum End Shears S , Moments 31 , and Reactions R for Live Loads (only), on Stringers and Eloor-Beams of Class E x . Span. Each stringer. Floor-Beams. Single track. Double track. L. S. M. Least R. M. R. M. Ft, Lbs. 1 uuu inch-lbs. size. Lbs. Lbs.-ft. Lbs. Lbs.-ft. 10. 12 000 360 12 000 24 000 11. 13 100 396 12-in. I. 12. 14 000 432 13. 14 800 468 14. 15 400 504 15. 16 000 540 10. 16 500 576 17. 16 900 612 | 18. 17 300 676 15-in. I. 1 1 19. 17 700 743 [S 1 20. 18 000 810 • 21. 18 300 878 22. 18 500 946 II 1 « 23. 18 800 1 014 18-in. I. II II II ll 24. 19 000 1 083 03 !a 03 25. 19 200 1 152 20. 19 400 1 221 27. 19 600 1 291 20-in. I. 28. 19 700 1 360 19 900 1 430 30. 20 000 1 500 20 000 40 000 Moment for stringers equals pi M = — up to 17 feet. n _5)2 M = P ——— over 17 feet, in foot-pounds. S — end shear of one stringer. M— maximum moment. P = concentrated load on one wheel. I — span in feet. d = distance in feet, center to center of trusses, e = distance in feet, center to center of tracks. f = “ “ “ ' “ stringers. 10 . 11 . 12 . 13. 14. 15. 16. 17, 18. 19. 20 . 21 . 22 , 23. 24, 25. 26. 27. 28. 29. 30. 35 TABLE II. Same for Class E 2 . Each stringer. 8. Lbs. M. 1 000 incb-lbs. Least size. 9 000 270 10-in. I. 9 800 297 10 500 324 11 100 351 11 600 378 12-in. I. 12 000 405 12 400 432 12 700 459 13 000 507 13 300 557 13 500 607 13 700 658 15-in. I. 13 900 709 14 100 761 14 200 812 14 400 864 14 500 916 18-in. I. 14 700 968 14 800 1 020 14 900 1 073 15 000 1 125 20-in. I. Floor-Beams. Single track. Double track. R. ■ M. R. M. Lbs. Lbs. ft. Lbs. Lbs. ft. - Q ✓—v I 'e 1 2d 2 Q |(N 2Q II II II ii 0$ TABLE ill. Maximum End Shears* S, Moments M and Beactions R fcr Live Loads (only) on Stringers and Floor-Beams of Classes A and B, with Double-Track Railway. t * 36 w a eg co S 3 w « i ps o o ij £ >> eg f£ OS eg O u o PS w C5 55 t-t PS E-i m w D ◄ & £ T 3 eg O f-i OS fl £ P Is ^ +3 a eg ft 03 -M R. Lbs. 888888883888888833888 OPOO®3kC»c5'^ , s3ajino»nojeocDo:o3Tt«oJ!OMt'OWinN®fficoooo r^MCOOOOOi'i'lONXOrttJCO'^lONCOOO-rt eococoeoTt'Tf-rf’Tr'^'^ioiCiOiCiOmicioocOsO 32 ft. R. Lbs. OOOQOOOOOOOOQOOOOOCQQ OOOOOOOOOOOOOOOOOOOOO ONOriMWOTPi>0:OrtHrfOOiX®1 , OIO 0)H'#ffii-.0irt«0?T»fflt-X03OOrtNMM'10 ojcoeoeoeoso'^'^-^'Tf'i''^'^ , '^ , in»o»ninin»nio 28 ft. 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