COST OF DRAFTING. 429 



Deck beams and bulb angles 1.75 



Checkered and corrugated plates 1.75 to 1.90 



1 Mates, structural, base 1.40 



Plates, flange, base 1.50 



Corrugated steel No. 22, painted 2.15 



Corrugated steel No. 22, galvanized 3.00 



Steel sheets Nos. 10 and 1 1 , black 1 .90 



Steel sheets Nos. 10 and 1 1 , galvanized 2.35 



Steel sheets No. 22, black 2.10 



Steel sheets No. 22, galvanized 2.95 



Bar iron, base 1 .65 



Rivets 2.10 



COST OF FABRICATION OF STRUCTURAL STEEL. The cost of fabrication of 

 structural steel may be divided into (a) cost of drafting, (b) cost of mill details, and (c) cost of 

 shop labor. 



(a) COST OF DRAFTING. The cost of drafting varies with the character of the structure 

 and with the shop methods of the bridge company. There are two general methods in common 

 use for detailing steel structures, sketch details, and complete details (see Chapter XII). The 

 cost of drafting varies with the method of detailing and the number of pieces to be made from 

 one detail, and costs per ton may mean but little and be very misleading. The cost per standard 

 sheet (24 in. X 36 in.) is more nearly a constant and varies from $15 to $25 per sheet. The 

 following approximate costs, based on a total average charge of 40 cents per hour may be of value. 



Mill and Mine Buildings. Details of ordinary steel mill buildings cost from $2 to $4 per 

 ton; details for head works for mines cost from $4 to $6 per ton; details for churches and court 

 houses having hips and valleys, cost from $6 to $8 per ton; details for circular steel bins cost 

 from $1.50 to $3 per ton; details for rectangular steel bins cost from $2 to $4 per ton; details for 

 conical or hopper bottom bins cost from $4 to $6 per ton. 



Bridges. Details of steel bridges will cost from $i to $2 per ton where sketch details are 

 used and from $2 to $4 per ton where the members are detailed separately. 



Actual Cost of Drafting. The details of the Basin and Bay State Smelter, containing 270 

 tons, cost $2 per ton. 



The costs of making shop details for steel structures as given in the Technograph No. 21, 

 1907, by Mr. Ralph H. Gage, are given in Table II. 



TABLE II. 

 COST OF SHOP DRAWINGS. 



Character of Building. 



Average Cost per Ton. 



Entire skeleton construction, i. e., loads all carried to the foundation by means 

 of steel columns 



Interior portion supported on steel columns; exterior walls carry floor loads 

 and their own weight 



Interior portion carried on cast iron columns; exterior waHs support floor loads 

 as well as their own weight 



No columns and floorbeams resting on masonry walls throughout 



Structure consisting mostly of roof trusses resting on columns 



Structure consisting mostly of roof trusses resting on masonry walls 



Mill buildings 



Flat one-story shop or manufacturing buildings 



Tipples, mining structures or other complicated structures 



Malt or grain bins and hoppers 



Remodeling and additions where measurements are necessary before details 



can be made 



$1.45 



1.22 



0.70 

 0.85 

 2.47 



"I 



2.56 



0.74 

 4.88 



2-47 

 1.87 



