STEEL FRAMEWORK OF BUILDINGS 5 



(a) A xial tension in main members, net section 16,000 Ibs. 



in wind bracing, " 20,000 " 



(6) Bending, net section, on extreme fibers of: 

 Rolled shapes, built sections and 



plate girders 16,000 Ibs. 



Pins 20,000 " 



(c) Axial compression in main members, gross section, 



S= 16,000 -70^-, 



where S= allowable unit stress. 



I = unsupported length of member in inches. 



r = least radius of gyration of member in inches. (Per. 39.) 



(d) Shear on: Turned bolts, and field rivets 



when hand driven 7,500 Ibs. 



Field rivets when power driven. 9,000 " 



Shop rivets and pins 10,000 " 



Plate girder webs, gross section. 10,000 " 



(e) Bearing on: Turned bolts and field rivets 



when hand driven 15,000 " 



Field rivets when power driven. 18,000 " 



Shop rivets and pins 20,000 " 



13. Expansion Rollers. 



Allowable pressure per lin. in 600d 



where d= diameter of roller in inches. 



14. Combined Stresses. When the effect of bending stresses 

 due to wind loading is considered and added to the axial and 

 bending stresses, due to other causes, the above unit stresses 

 (Par. 12) may be increased 25 per cent. 



15. Eccentric Stresses. Provision must be made for eccen- 

 tric loading on columns and other members. Whenever angles 

 used as web members or bracing are connected up by one leg 

 only, the above unit stresses (Par. 12) shall be decreased 25 per 

 cent. 



1 6. Reversal of Stresses. Members and connections sub- 

 ject to reversal of stresses shall be proportioned for an equivalent 

 stress equal to that stress which, when added to 50 per cent of 

 the other, will give the greater section. 



