$18\mathrm{.}7$ Two $C1020$ s are bolted to a gusset plate by four

rows of $\frac{7}{8}-$in$.-$diameter bolts as shown. The channels

are made of A$36$ steel. Determine their tensile capacity

if the type and total number of bolts are as follows:

a$.A325-F,N=12.$

b$.$ A$325-$N$,N=12.$

Note: Because the load is transmitted by bolts through only

part of the channel $($web$)$ and there are at least three bolts in

the direction of stress, the net area is only $85$ percent effec$-$

tive $($AISC Specifications$).$

$n$@$2-\frac{1}{4}$ in$.=n2-\frac{1}{4}$ in$.$