SPECIFICATIONS 



395 



Duchemin 



Mutton 



Straight Line - - - 



FORMULAS 

 Duchemin 

 Mutton 

 Straight Line fi=A,(A *45') 



Normal Pressure,lbs-per sqft- 



/^Horizontal' 



A =Angle of inclination of surface 



15 20 5 30 .35 40 45 5O. 55 60 65 70 75 80 85 



Angle Exposed Roof makes with Horizontal in Degrees, A. 



FIG. 2. NORMAL WIND LOAD ON ROOF ACCORDING To 



FORMULAS. 



PROPORTION OF PARTS. 



27. In proportioning the different parts of the structure 

 the maximum stresses due to the combinations of the dead and 

 wind load ; dead and snow load ; or dead, minimum snow and 

 wind load are to be provided for. Concentrated loads where 

 they occur must be provided for. 



28. Allowable Unit Tensile Stresses for Medium Steel. 



Pounds per 

 square inch 

 Shapes, main members, net section .......... 16,000 



Bars ..................................... 16,000 



Bottom flanges of rolled beams .............. 16,000 



Shapes, laterals, net section. . . ............. 20,000 



Iron rods for laterals ..................... 20,000 



Plate girder webs, shearing on net section ---- 10,000 



Stresses. 



Tensile Stress. 



