A T-beam behaves as a rectangular beam of a width equal to its flange if its neutral axis

ANS:A - remains within the flange

1) When NA lies in flange then;

The stress block dig above NA is a rectangular parabola. So stress distribution is linear
TF= 0.87fy.Ast.
CF= 0.36.fck.bf.

(2) when NA falls in Web.
Stress in the flange is not uniform so analysis becomes difficult;
-Stress changes the constant value after the depth (3/7).