RECTANGULAR BEAMS 127 



a = a numerical coefficient depending on p and n. 

 /c =5 proportionate depth of the neutral axis. 

 G! = the numerical coefficient in the formula for deflec- 



Wl 3 

 tion of homogeneous beams, c i~pT' depending on 



the loading and support. For example, 

 for a cantilever loaded at the end, c t = 



o 



for a cantilever uniformly loaded, C = Q 



o 



for a simple beam loaded at center, c 1 =-r, 



4o 



for a simple beam uniformly loaded, c = 



for a beam with fixed ends, load at the 

 center, c t = 



for a beam with fixed ends, uniformly 

 loaded, 



384 



384 



The following are the deflection formulas for reinforced concrete 

 T-beams (referred to later) : 



D -^.^. n 

 ~E. bd* p 



k = 



b b\d 



in which ft is a coefficient depending upon the steel ratio and n, 

 and other symbols as before. 



Illustrative Problem. A rectangular reinforced concrete beam with 6 = 18 

 in. and d = 27 1/2 in. has a span of 40 ft. and is reinforced with four 11/8 

 in. round rods (and stirrups) extending along the whole length. What is 

 its probable deflection when sustaining a uniform load of 600 Ib. per foot, 



