Problem 8. A crane (see figure below) is used to move concrete manhole sections
ID: 1921166 • Letter: P
Question
Problem 8. A crane (see figure below) is used to move concrete manhole sections that weigh 2500 lbs each. A steel cable composed bound strands of wire 1/16?? in diameter support the load. If the allowable stress for the steel is 30000psi, how many strands of steel wire are required in the cable to support a manhole section? Cable Problem 9. A 3/4 inch diameter bolt experiences a shear stress of 20.37 KSI when loaded in single shear as shown in the figure below. Determine the force F in kips that that will cause this amount of stress.Explanation / Answer
area of a wire = pi/4 * (1/16)^2 = 0.00306 in^2
total load bourne by one wire = .00306 * 30000 = 92.039 lb
for one manhole
no. of wires required = 2500 / 92 = 28 wires so 4 strands each of 7 wires.
B force = 20.37 * pi/4 *(3/4)^2 = 9 kips