58 



W. H. WARREN. 



increases. The diagram shows that the neutral axis for a 

 bending moment of 181*25 inch tons is 1*9 inches from the 

 centre, and for the mean bending moment obtained, in 

 testing the four beams 199*4 inch tons, the neutral axis 

 would be nearer to the extreme fibre in compression. The 

 stress curves derived from the strain curves are fairly 

 straight for a bending moment about one-third of that pro- 

 ducing fracture, but they are curved for greater bending 

 moments, curves 4 and 5 being approximately parabolic. 

 Fig. 7 shows the results of testing beams III., IV., V. and 



Fig. 7 — Curves showing the distribution of the Compressive Stresses over the 

 Cross Section of a Reinforced Concrete Beam as obtained by experiment. 



Compressive Stress pounds per square inch. 



o © o o o o 

 ©©©©©© 



N O 00 tO ^ N 



Compressive Stress pounds per square inch. 



Reference. 

 No. III. 1:2:3 Concrete, three f in. bars. 1 Bending Moment = 32*25 in. tons. 

 No. IV. 1 : 2 : 3 „ „ $ in. bars. 2 „ „ = 725 



No. Y. 1 : 2 : 2 „ „ | in. bars. 3 „ 10875 „ 



No. VI. 1 : 2 : 3 „ „ 1 in. bars. 4 „ 1350 



Age about 360 days. 



