Question

A prismatic beam AB of length 12 m is subjected to two point loads of 80 kN and a couple of magnitude 30 kN-m as shown below :

The moment reaction developed at end 'A' is

• A. 28 kN-m
• B. 305 kN-m
• C. 30.5 kN-m
• D. 280 kN - m

Answer 1

The correct option is B 305 kN-m

Due to all loads, the net rotation of end 'A' should be zero.


$\frac{M_A\times 12}{3EI}-\frac{80\times 4\times 8(12+8)}{6\times 12\times EI}-\frac{80\times 8\times 4\times (12+4)}{6\times 12\times EI}+\frac{30\times 12}{6EI}=0$

$\Rightarrow M_A=305kN-m$