Written Problem:

$(\backslash (\backslash$mathbf$\{50\}\backslash$mathbf$\{$~ p t s$\}\backslash ))$: Using LRFD$,$ determine the design capacity for the member shown. The member is a cross frame that carries tension when the wind is eastward and compression when the wind is westward. The member is a channel section with sectional properties shown below. The member is supported in the weak direction by the other diagonal member. All connections are pinned connections. Assume $\backslash (\backslash$mathrm$\{$U$\}=0\mathrm{.}85\backslash ).$

Bolts A$325,\backslash (3/4\backslash )$ in$.$ dia.

$\backslash ($ F y$=70\backslash$mathrm$\{$ks$\}\backslash )$

sender$/$non slender

controlling Lcrlatio design compressive strength design strength as tensan member.

$1.$ Determine if the section is slender or non slender based on the slenderness parameters from Table B$4\mathrm{.}1$

$2.$ Determine the controlling Lc$/$r ratio

$3.$ Determine the design compressive strength of the number considering flexueal buckling. Neglect torsional buckling. Use LRFD$.$

$4.$ When the wind changes direction, the member acts as a tension member. Determine the design strength as a tension member. Assume U$=0\mathrm{.}85.$ Neglect block shear. Use LRFD$.$