A ship's spar is attached at the base of a mast by a pinconnection. The spar is a steel tube of outer diameter d2=80mm and inner diameter d1=70mm. The steel pin has diameter d=25mm , and the two plates connecting the sparto the pin have thickness t = 12 mm.
The allowable stresses are as follows:compressive stress in the spar, 70 MPa; shear stress in the pin, 45MPa; and bearing stress between the pin and the connecting plates,110 MPa.
Determine the allowable compressive force Pallowin the spar.