If the section shown in the figure turns from fully-elastic to fully-plastic, the depth of neutral axis (N.A.), y , decreases by

Q. If the section shown in the figure turns from fully-elastic to fully-plastic, the depth of neutral axis (N.A.), y , decreases by

(A) 10.75 mm

(B) 12.25 mm

(C) 13.75 mm

(D) 15.25 mm

Ans: 13.75 mm

Solution:

For fully elastic case,

For fully plastic case,
Equal area axis at y = 5 mm
N.A reduces by = 18.75 – 5 = 13.75 mm