and 



Bresse's Equation 



(a. )p = ^-^(i) n (5) 



Using V = 0.20 and the approximation R = D /2, Donnell's equation 

 becomes 



1 . 25 E . n 



o 



and Bresse's Equation 



2 

 iG,J^ = 1.04 E,. nf^^ (8) 



im^B i ' D 



The elastic condition exists when n = 1 • 



E. was not measured for each specimen so an empirical relationship 

 was developed to calculate its value. Figure 4 shows the experimental 

 initial elastic moduH data as a function of compressive strength. The 

 American Concrete Institute (ACI) expression for elastic moduli is 

 shown for comparison along with the empirical expression: 



= 530 f (9) 



10 



