Problem 919 | Additional Axial Compression Load for the Section to Carry No Tensile Stress

The largest tensile stress is at corner B
$\sigma_B = 320 ~ \text{psi}$

$P_2 = 19,200 ~ \text{lbs}$   ←   answer

$\sigma_B = 320 ~ \text{psi}$

$\sigma_C = 80 ~ \text{psi}$

$\sigma_D = -720 ~ \text{psi}$

$\sigma_B = 320 - 320 = 0$

$\sigma_C = 80 - 320 = -240 ~ \text{psi}$

$\sigma_D = -720 - 320 = -1040 ~ \text{psi}$

See figure above.