402 STRUCTURAL DRAFTING. CHAP. XII. 



Pin-connected Truss Bridges. In pin-connected truss bridges detail the left half of the far 

 truss as seen from the inside, every member by itself. It is generally best to commence with the 

 end-post, showing it lengthwise on the sheet with the lower end to the left; then the first section 

 of the top chord, and so on. The packing at panel points shall, whenever possible, be so arranged 

 that, besides the customary allowance of & in. for every bar, a clearance of not less than f in. can 

 be provided between the two sides of the chord. When two or more plates are used, -55 in. should 

 in addition be allowed for each plate. Members shall be marked the same as for riveted truss 

 bridges, with the panel points between which they go, see Fig. 7. 



Order of Detailing Truss Spans. In making detail plans and bills of material the following 

 order shall be followed for truss spans. 



1. General drawing; 7. Upper laterals; 



2. End-posts; 8. Lower laterals; 



3. Upper chords; 9. Floorbeams; 



4. Lower chords; 10. Stringers; 



5. Intermediate posts; n. Castings, bolts, eye-bars, pins, etc. 



6. Sway bracing; 



OFFICE BUILDINGS AND STEEL FRAME BUILDINGS. Number of Drawings. The 

 different sheets shall be numbered consecutively, whether large or small. No half numbers are 

 permissible except in emergency cases. It is always well to arrange the number so that the sheets 

 follow in the order in which the material is required at the building. The following is generally 

 a good order: 



1. Floor plans for all floors; 



2. Column schedule; 



3. Cast-iron bases for columns; 



4. Foundation girders; 



5. Foundation beams; 



6. First tier of columns; 



7. Riveted girders, connecting to first tier of columns 



8. Beams connecting to first tier of columns; 



9. Miscellaneous material for above; 

 10. Second tier of columns, etc., etc. 



Floor Plans. Floor plans, Fig. 12, shall, as a rule, be made to a scale f in. to i ft. A separate 

 plan shall be made for each floor, unless they are exactly alike. Columns shall be marked consec- 

 utively with numerals, the word Col. always appearing in front of the numeral, for example, 

 Col. 20. The architect or engineer has generally on his drawing adopted a system of marking for 

 the columns, which should be adhered to, unless altogether too impracticable. Riveted girders 

 shall be indicated with two (2) fine lines when they have cover plates, and with four (4) fine lines 

 when they have no cover plates. They shall be marked consecutively with numerals, using the 

 same marks for girders which are alike. Beams and channels shall be indicated with one single 

 heavy line. They shall be marked the same as girders, with numerals, using same marks when 

 alike. Tie-rods shall be indicated with one single fine line; they need not have any marks. The 

 marking system shall be as uniform as possible for the different floors, i. e., a beam which goes 

 between Col. 2 and Col. 3 shall be marked with the same numeral throughout all the floors. All 

 figures necessary for making the details shall, as a rule, appear on the floor plan, care being taken 

 in writing same to leave room for the erection marks, which must be printed in heavy type above 

 the line or lines representing a beam or girder. 



Column Schedule. For every large building a schedule of the columns shall be made before 

 the details are started, see Fig. 13. Each column, even should several be alike, shall have a separ- 

 ate space, in which shall be given the material and the finished length. As soon as the detail 

 drawings for one tier of columns are finished the sheet numbers shall be inserted as shown on the 

 sample schedule, Fig. 13, making the schedule serve as an index for the column drawings. 



