Chapter 13.6, Problem 79P

A long, slender structural aluminum [E = 69 GPa] flanged shape is used as al = 9.2-m-long column. The column is supported in the x direction at base A and pinned at ends A and C against translation in the y and z directions. Lateral support is provided to the column so that deflection in the x-z plane is restrained at mid-height B; however, the column is free to deflect in the x-y plane at B. Assume that b; = 102 mm, d = 122 mm, t; = 8 mm, and tw = 6 mm. Determine the maximum compressive load P the column can support if a factor of safety of 2.9 is required. In your analysis, consider the possibility that buckling could occur about either the strong axis (i.e., the z axis) or the weak axis (i.e., the y axis) of the aluminum column. P bf C L d Lateral B bracing L

(a) Explain FIVE (5) factors that may influence the optimum column design under an axial compressive load. (b) A 3.6 m long pin-ended column is formed from an A-36 steel circular hollow section with an outer diameter of 75 mm. Determine the minimum thickness, t (to the nearest integer in mm) of the circular hollow section so that the column can safely support the load of 200 kN without buckling. If the outer diameter of the steel circular hollow section is reduced to 62 mm and the ends are pinned-fixed supported, analyse whether the column with the same applied load and the sectional thickness computed above will cause a buckling failure.

Determine the longest length of a W8 * 31 structural A992 steel section if it is pin supported and is subjected to an axial load of 130 kip. Use the AISC equations.