Use virtual work method to solve the probiems:

$($a$)$

Find ${}_B$ in horizontal and vertical direction.

$=200$GPa

$=60{10}^{6}m{m}^4$

$($b$)$

Element BD is $5$ mm too long.

Find ${}_B$ in horizontal and vertical direction.

$E=200$GPa

$A=4000m{m}^2$

Use Castigliano's theory method to solve the problems :

$($a$)$

Find ${}_B,{}_C,{}_D$

$E=200$GPa

$I=50{10}^{6}m{m}^6$

$($b$)$

Find ${}_G,{}_B$ in horizontal direction.

$E=200$GPa

$A=5000m{m}^2$