Question $6$

The double$-$web girder is constructed from two plywood sheets that are secured to wood members at its top and bottom. The allowable bending stress for the wood is ${}_{\text{a}\text{l}\text{l}\text{o}\text{w}}=8$ksi and the allowable shear stress is ${}_{\text{a}\text{l}\text{l}\text{o}\text{w}}=3$ksi. If the fasteners are spaced $s=6in.$ and each fastener can support $600$ lb in single shear, determine the maximum load $P$ that can be applied to the beam.