For the column shown below with f'c = 35 MPa and fy = 420 MPa, compute the strength values
at points A-I in the interaction diagram. Plot the interaction diagram (including nominal strength
and design strength curves).
Solution
The design strength at point A(pure compression ) will be because of concrete that
Pu = 0.4*fc*b*d
= 0.4*35*460*460/1000
= 2962.4 KN
The design strength at point I(pure tension ) will be because of steel that
0.87*fy*Ast = 0.87*420*3*3.14*292/4/1000
= 723.7 KN
The design strength are calculated assuming the Indian codes of structural design. If you have
any doubt, post it in comments.