$2\mathrm{.}2-14$ The three$-$bar truss ABC shown in the figure

part a has a span $L=3m$ and is constructed of steel

pipes having a cross$-$sectional area $A=3900m{m}^2$

and modulus of elasticity $E=200$GPa. Identical

loads $P$ act both vertically and horizontally at joint

$C,$ as shown.

$($a$)$ If $P=475kN,$ what is the horizontal displace$-$

ment of joint $B?$

$($b$)$ What is the maximum permissible load value

$P_{\text{m}\text{a}\text{x}}$ if the displacement of joint $B$ is limited to

$1\mathrm{.}5mm?$