Question

A simply supported beam of span length $6m$ and $75mm$ diameter carries a uniformly distributed load of $1.5kN/m$.

What is the maximum value of bending stress?

• A. 162.98MPa
• B. 325.95MPa
• C. 625.95MPa
• D. 651.90MPa

Answer 1

The correct option is A 162.98MPa

$R_A+R_B=9kN$
Taking moment about B, we get
$\therefore R_A\times 6=1.5\times 6\times 3$
$R_A=R_B=4.5kN$
$M_{max}=4.5x-1.5\frac{x^2}{2}[atx=3m]$
=6.75kNm




We know that
$\frac{M}{I}=\frac{{\sigma }_b}{y}$


$\therefore {\sigma }_b=\frac{6.75\times {10}^6\times 64}{\pi \times {\left(75\right)}^4}\times \frac{75}{2}=162.97MPa$