Three 1 X 18-in. steel plates are bolted to four L6 X 6 X 1 angles to form a beam with the cross section shown. The bolts have a 7/8-in. diameter and are spaced longitudinally every 5 in. Knowing that the allowable average shearing stress in the bolts is 12 ksi, determine the largest permissible vertical shear in the beam. (Given: Ix = 6123 in4.)
