Question

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

• A. 15.25 mm
• B. 10.75 mm
• C. 12.25 mm
• D. 13.75 mm

Answer 1

The correct option is D 13.75 mm


For fully elastic case,
$\overline{y}=\frac{60\times 5\times \frac{5}{2}+60\times 5\times (5+\frac{60}{2})}{60\times 5+60\times 5}$

$=\frac{750+10500}{2\times 60\times 5}=18.75$

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