Use conjugate beam method and virtual work method to solve the following problems.$($Beam$)$

$(1)$

Find ${}_B^{\text{'}}{}_{BL}^{\text{'}}{}_{BR}$

$E=200$GPa

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

$A=5000m{m}^2$

Find P such that ${}_c=0$

$E=200$GPa

$I=40{10}^{6}m{m}^4$

$A=7000m{m}^2$

Use virtual work method to solve the following problem.$($Truss$)$

Find ${}_B$ in vertical and horizontal directions

$E=200$GPa

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

$A=5000m{m}^2$