$\delta = \delta_T + \delta_{st}$
$\dfrac{\sigma \, L}{E} = \alpha \, L \, (\Delta T) + \dfrac{PL}{AE}$
$\sigma = \alpha \, E \, (\Delta T) + \dfrac{P}{A}$
$130 = (11.7 \times 10^{-6})(200\,000)(40) + \dfrac{5000}{A}$
$A = \dfrac{5000}{36.4} = 137.36 \, \text{ mm}^2$
$\frac{1}{4} \pi d^2 = 137.36$
$d = 13.22 \, \text{ mm}$ answer