Module 7 Worked Examples: Steel Compression Members

A steel column has $K=1.0$, $L=3.0\text{ m}$, and $r=60\text{ mm}$. Find $KL/r$.

For the same $3.0\text{ m}$ column, let $r_x=100\text{ mm}$ and $r_y=50\text{ mm}$ with $K=1.0$ in both directions. Determine the governing axis.

Use $E=200{,}000\text{ MPa}$ and $KL/r=60$. Determine $F_e$.

Let $F_y=345\text{ MPa}$ and $F_e=548.3\text{ MPa}$. Use the inelastic NSCP compression-curve expression to determine $F_{cr}$.

A nonslender column has $A_g=6{,}000\text{ mm}^2$ and $F_{cr}=265.0\text{ MPa}$. Determine $P_n$ and, for this stated LRFD compression case, use $\phi_c=0.90$ to determine available compressive strength.

A column with $r=50\text{ mm}$ has an unbraced length of $4.0\text{ m}$. A brace is added at midheight so each segment is $2.0\text{ m}$, with the same idealized $K=1.0$. Compare slenderness.

A reviewer describes an axially loaded column flange as "compact." What terminology should the compression-member review use?

A slender single-angle compression member is proposed. Is a major- and minor-axis flexural check automatically complete?

Two candidate columns have similar area, but one HSS has comparable radii of gyration about both axes while a W-shape has a much smaller weak-axis radius. What is the stability implication?

An exposed lobby column is becoming too large because of its weak-axis unbraced length. Give two structural strategies other than simply increasing area.

A steel column has physical length $L=3{,}000\text{ mm}$ and radius of gyration $r=50\text{ mm}$ about the axis being checked. Compare idealized end conditions.

For a stated compression-member case, the applicable Section 505/E7 element checks have already produced $Q=0.80$. Let $F_y=345\text{ MPa}$, $F_e=200\text{ MPa}$, and $A_g=5{,}000\text{ mm}^2$. Determine the stated flexural-buckling strength and LRFD available strength.