A symmetric frame $$PQR$$ consists of two inclined members $$PQ$$ and $$QR$$, connected at $$‘Q’$$ with a rigid joint, and hinged at $$‘P’$$ and $$‘R’.$$ The horizontal length $$PR$$ is $$l.$$ If a weight $$W$$ is suspended at $$‘Q’,$$ the bending moment at $$‘Q’$$ is