QUESTION $6(20$ marks$)$

a$)$ Design the formwork for an elevated concrete floor slab $6$ in$.$ thick. Sheathing will be $1-$in $($nominal$)-$thick lumber, while $28$ in$.$ lumber will be used for joists. Stringer will be $48$ in$.$ lumber. Assume that all members are continuous over three or more spans. Commercial $4000-lb$ shores will be used. It is estimated that the weight of the formwork will be $5l\frac{b}{s}qft.$ The adjusted allowable stresses for the lumber being used are as shown in Table $3$ below:

$\backslash$table$[[,$Sheathing $($psi$),\backslash$table$[[$Other$],[$Members $($psi$)]]],[F_b,1075,1250],[F_v,174,180],[,,345],[F_c,,850],[E,1\mathrm{.}36{10}^6,1\mathrm{.}4{10}^6$