80 



STANDARD SPECIFICATIONS 



(6) The modulus of elasticity of concrete in compression 

 is constant, and the relation of stress to strain in con- 

 crete is rectilinear. 



(c) In calculating the moment of resistance of slabs, beams, 

 or girders the tensile value of the concrete shall be 

 neglected. 



344. Bending Moments. The bending moments shall be 

 computed as follows: 



(a) For slabs, reinforced in one direction only, 



When supported at both ends,M= 1.5wL 2 , at center 



= at ends 



When supported at one end, | M= ^ 

 continuous at other 



f at one end 

 = \-1.2wL 2 at the other. 



When continuous, or fixed *\M=wL 2 , at center, 

 at both ends, = wL 2 at ends, 



where M = bending moment in inch-pounds; 



w dead or live load in pounds per linear foot, uniformly 



distributed ; 

 L = length of span in feet. (Par. 342.) 



(6) For slabs whose length does not exceed 1J times their 

 width and which are reinforced in both directions, 

 the loading shall be assumed to be divided between the 

 transverse and the longitudinal systems, as follows: 



and shall be distributed to the supporting beams in a 

 variable ratio, increasing toward the center as the 

 ordinates of a triangle. 



(c) For beams and girders the bending moments shall, aside 

 from loading, depend upon the end conditions, as given 

 above, under (a). 



