Compute the compressive strength of a WT12 x81 of A992 steel. The effective length with respect to the x-axis is 25 feet 6 inches, the effective length with respect to the y-axis is 20 feet, and the effective length with respect to the z-axis is 20 feet.

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Step 1Find, compute the flexural buckling strength for the x-axis (the axis of no symmetry):Lcxrx=25.5*123.50=87.43Fe=π2E(Lc/r)2=π2(29000)(87.43)2=37.44ksiEFy4.71=29000504.71=113Step 2Since Lcxrx<4.71EFy, AISC Equation E3-2 applies:Fcr=0.658(Fy/Fe), Fy=0.658(50/37.44)(50)=28.59ksiThe nominal flexural buckling strength isPn=FcrAg=28.59(23.9)=683.3kipsCompute the flexural-torsional buckling strengthabout the y-axis(the axis of symmetry):Lcyry=20*123.05=78.69Fey=π2E(Lcy/ry)2=π2(29000)(78.69)2=462.2305ksiFrom equation 4.14,Fez=GJAgr02¯Because the shear center of a tee is located at the intersection of the centerlines of the flange and the stem,xo=0 ... See the full answer