GENERAL SPECIFICATIONS FOR STEEL FRAME BUILDINGS.* 



BY 



MILO S. KETCHUM, 

 M. Am. Soc. C. E. 



THIRD EDITION. 

 1914. 



GENERAL DESCRIPTION. 



1. Height of Building. The height of the building shall be the distance from the top of the 

 masonry to the under side of the bottom chord of the truss. 



2. Dimensions of Building. The width and length of the building shall be the extreme dis- 

 tance out to out of framing or sheathing. 



3. Length of Span. The length of trusses and girders in calculating stresses shall be con- 

 sidered as the distance from center to center of end bearings when supported, and from end to 

 end when fastened between columns by connection angles. 



4. Pitch of Roof. The pitch of roof for corrugated steel shall preferably be not less than 

 J (6 in. in 12 in.), and in no case less than . For a pitch less than some other covering than 

 corrugated steel shall be used. 



5. Spacing of Trusses. Trusses shall be spaced so that simple shapes may be used for 

 purlins. The spacing should be about 1 6 ft. for spans of, say, 50 ft. and about 20 to 22 ft. for 

 spans of, say, 100 ft. For longer spans than 100 ft. the purlins may be trussed and the spacing 

 may be increased. 



6. Spacing of Purlins. Purlins shall be spaced not to exceed 4 ft. 9 in. where corrugated 

 steel is used, and shall be placed at panel points of the trusses. 



7. Form of Trusses. The trusses shall preferably be of the Fink type with panels so sub- 

 divided that panel points will come under the purlins. If it is not practicable to place the purlins 

 at panel points, the upper chords of the trusses shall be designed to take both the flexural and 

 direct stresses. Trusses shall preferably be riveted trusses. 



Trusses supported on masonry walls shall have one end supported on sliding plates for spans 

 up to 70 ft., for greater lengths of span rollers or a rocker shall be used. No rollers with a 

 diameter less than 3 in. shall be used. 



All field connections of the steel framework shall be riveted except the connections for purlins 

 and girts, which may be field bolted. 



8. Bracing. Bracing in the plane of the lower chords shall be stiff; bracing in the planes of 

 the top chords, the sides and the ends may be made adjustable. 



9. Proposals. Contractors in submitting proposals shall furnish complete stress sheets, 

 general plans of the proposed structures giving sizes of material, and such detail plans as will 

 clearly show the dimensions of the parts, modes of construction and sectional areas. 



10. Detail Plans. The successful contractor shall furnish all working drawings required by 

 the engineer free of cost. Working drawings will, as far as possible, be made on standard size 

 sheets 24 in. X 36 in. out to out, 22 in. X 34 in. inside the inner border lines. 



11. Approval of Plans. No work shall be commenced or materials ordered until the working 

 drawings are approved in writing by the engineer. The contractor shall be responsible for dimen- 

 sions and details on the working plans, and the approval of the detail plans by the engineer will 

 not relieve the contractor of this responsibility. 







LOADS. 



12. The trusses shall be designed to carry the following loads: 



13. DEAD LOADS. Weight of Trusses. The weight of trusses per sq. ft. of horizontal 

 projection, up to 150 ft. span shall be calculated by the formula 



where W = weight of trusses per sq. ft. of horizontal projection; 



P = capacity of truss in pounds per sq. ft. of horizontal projection; 



L = span of the truss in feet; 



A = distance between trusses in feet. 



* Reprinted from the author's " The Design of Steel Mill Buildings." 



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