Question

In case of a simply supported $I-$section beam of span $L$ and loaded with a central load $W$, the length of elasto-plastic zone of the plastic hinge is

• A. $\frac{L}{2}$
• B. $\frac{L}{3}$
• C. $\frac{L}{4}$
• D. $\frac{L}{5}$

Answer 1

The correct option is D $\frac{L}{5}$

The length of elasto-plastic zone of the plastic hinge is given by:

$l_p=L(1-\frac{1}{\text{shape factor}})$

where,
$l_p=$ Length of elasto-plastic zone
$L=$ Span

$Shapefactor=1.1to1.2forI-section$

$\therefore l_p=L(1-\frac{1}{1.2})=L(1-\frac{5}{6})=\frac{1}{6}$

$Hence,\begin{array}{c}{l}_p=\frac{L}{6}\end{array}$

Notes: Although, according to option (d), the shape factor will be 1.25 for I-section shape factor =1.1 to 1.2, therefore, the nearest option is (d).