$9\mathrm{.}8-8$ A composite floor system consists of steel beams supporting a formed steel deck and concrete slab. The deck is shown in Figure P$9\mathrm{.}8-8,$ and the total depth from bottom of deck to top of slab is $\frac{61}{2}$ inches. Lightweight concrete is used $($unit weight $=115pcf),$ and the $28-$day compressive strength is $4$ ksi $.$ The deck and slab combination weighs $53$ psf $.$ The beams are spaced at $12$ feet, and the span length is $40$ feet. There is a $20$psf construction load, a partition load of $20$ psf $,$ other dead load of $10$ psf $,$ and a live load of $160$ psf $.$ The maximum permissible live$-$load deflection is $\frac{L}{360}.$ Use the composite beam tables and select a W$-$shape with $F_y=50$ ksi $.$ Design the stud anchors. Use partial composite action and a lowerbound moment of inertia.

a$.$ Use LRFD$.$

b$.$ Use ASD.