Question

A rectangular beam of size $350mm\times 750mm$ is subjected to a twisting moment of $150kN-m$ and a hogging bending moment of $180kN-m$. The grade of materials used are $M25$ and $Fe500$. The longitudinal reinforcement provided on the flexural compression face, is to resist the equivalent moment of ______k N-m. (round off to two decimals)

• A. 97

Answer 1

The correct option is A 97
Given, $M_u=180kN-m$
$T_u=150kN-m$
$(b\times D)=(350mm\times 750mm)$
Equivalent bending moment due to torsion
$M_e=\frac{T_u}{1.7}(1+\frac{D}{b})$
$=\frac{150}{1.7}(1+\frac{750}{350})$
$=277.31kN-m$
Here, $M_e>M_u$, so
The longitudinal reinforcement provided on the flexural compression face, is to resist the equivalent moment of
$M_{e2}=M_e-M_u$
$=(277.31-180)kNm$
$=97.31kN-m$