Question

A rectangular solid cross-section of the beam is subjected to negative / hogging bending moment of 20 kN-m . The tensile force acting on the shaded area of the cross- section developed by the bending stresses.

• A. 8.9 kN
• B. 45 kN
• C. 54 kN
• D. 10.64 kN

Answer 1

The correct option is C 54 kN

$F=\frac{{\sigma }_{b\left(max\right)}}{y_{max}}\times A\overline{y}$
${\sigma }_{b\left(max\right)}=\frac{\frac{20\times {10}^6}{100\times {200}^3}}{12}\times 100=30MPaA=100\times 20;\overline{y}=90$
$F=\frac{30}{100}\times (100\times 20)\times 90$
$F=54kN$