47 



provide steel for negative bending 



(12) Always 

 moment. 



(13) Provide shrinkage bars around all openings and 

 In all concrete place steel for shrinkage equal to 1-275 of 

 the total area per sq. ft. 



(14) Try to use bars not larger than one Inch, as too 

 large bars do not distribute the stresses through the con- 

 crete as well as small bars. 



(15) In designing high buildings be sure to Investigate 

 for wind bracing. 



STRESSES. 



Ef is 

 c - 15 



Concrete: Compression 600 Ib. per sq. In. in columns. 



Diagonal Tension 60 Ib. per sq. in. in beams. 



Compression, average 300 Ib. per sq. In. In beams. 

 Steel: Patented or twisted bar: 



Tension 20,000 Ib. per sq. In. 



Shear 12,000 Ib. 



Compression 10,000 Ib. per sq. in. (round bars). 



The neutral axis of a reinforced concrete slab can be 

 found from the following: 



d = thickness of s'ab. 



Crrdistanro ronti-r >f stool to bottom of slab, 

 ar distance from top of slab to the neutral axis. 

 \ v neutral axis. 



The total compressive stresses are applied at a point ~ 

 below the top of the slab. In all computations slabs are 

 generally figured for a width of b li! In 



The maximum Intensity of stress in tension la f s 

 In Ib. per sq. In. 



