A ship's spar is attached at the base of a mast by a pin connection (see figure).

Question:

A ship's spar is attached at the base of a mast by a pin connection (see figure). The spar is a steel tube of outer diameter d2 = 3.5 in. and inner diameter d1 = 2.8 in. The steel pin has diameter d = 1 in., and the two plates connecting the spar to the pin have thickness t = 0.5 in. The allowable stresses are as follows: compressive stress in the spar, 10 ksi; shear stress in the pin, 6.5 ksi; and bearing stress between the pin and the connecting plates, 16 ksi.
Determine the allowable compressive force Pallow in the spar.