Figure $2$ shows a frame structure with a pinned support at point A and a roller support at point C$.$ Inclined member $AB$ is subjected to a uniformly distributed load of $5k\frac{N}{m}$ acting perpendicularly to the member. A concentrated moment of $20kNm$ acts about point $B$ and a uniformly distributed loads of $12k\frac{N}{m}$ acts along member BC$.$ Use the virtual work method to determine the vertical displacement at B$.$ Take $E=200$GPa and $I=300{10}^{6}m{m}^4.$