Consider the roof system shown. The roof is supported by stud walls around the exterior, and a cantilever roof beam system through the middle, as shown in the plan view below. The loads are as follows: roof dead load (D) due to five-ply felt and gravel composition roofing, -in. plywood, -in. thick rigid insulation, mechanical duct allowance, 2 x 10 Douglas-fir roof joists (actually 1.5 in. by 9.25 in.) at 16 inches on center, and beam weight; roof live load (L) of 20 psf; there is no snow load. Do not use live-load reductions. Assume the girder is a Douglas-fir glulam having width of 6-3/4 inches.