Challenge 1

Q-01: 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.

• The parabolic stress vs strain curve for concrete has been studied extensively.
• Attempts have been made to develop an algebric expression for the parabolic stress strain curve.
• One of the commonly used algebric expressions for the stress vs strain is Modified Hognested Parabola.

• IS 456:2000 adopts parabolic linear stress strain curve for concrete.
• The stress strain relationship is parabolic for strain up to 0.002 and linear thereafter.
• The IS code limits the failure strain of concrete to 0.002 under direct compression and 0.0035 under flexure.