Challenge 1

Aim: Plot stress-strain curve of concrete per modified Hognestad method and per IS 456-2000. Clearly show the characterisitic features of the stress-strain curves in both methods and compare them.

Explanation: Hognestad method used for research purpose.

maximum strain in concrete for hognestad method is 0.0038 where as per IS 456:2000 it is 0.0035

At max strain for hognestad stress strain curve is 0.15 times of ultimate strength of concrete,

As per IS 456:2000 failure strain of concrete to 0.002 under direct compression and 0.0035 under flexure means upto 0.002 it strain is parabolic then after it is linear.Where as for Hognestad parabolic upto eo=1.8(fc"/Ec) then after linear.

Stress strain graphs for both attached.