An alternative design for the bench described in Problem is to use the built-up wood T-sha...

An alternative design for the bench described in Problem is to use the built-up wood T-shape shown in Figure P8-30. The wood is to be No. 3 grade southern pine. One nail is to be driven into each vertical 2 X 12. Each nail can withstand 160 lb in shear, and the nails are spaced 6.0 in apart along the length of the beam. Compute the maximum allowable distributed load on the beam.

Problem

The shape in Figure is to be fabricated by riveting the bottom plate to the angles and then welding the top plate to the angles. When used as a beam, there are four potential failure modes: bending stress, shearing stress in the angles, shear in the welds, and shear of the rivets. The shape is to be used as the seat of a bench carrying a uniformly distributed load over a span of 10.0 ft. Compute the maximum allowable distributed load for the following design limits.

(a) The material of all components is aluminum 6061-T4, and a design factor of 4 is required for either bending or shear.

(b) The allowable shear flow ®n each weld is 1800 lb/in.

(c) The rivets are spaced 4.0 in apart along the entire length of the beam. Each rivet can withstand 600 lb of shear.

FIGURE

FIGURE