A Beginner's Guide to the Steel Construction Manual, 16^th ed.

Chapter 7 - Concentrically Loaded Compression Members

© 2006, 2008, 2011, 2017, 2023 T. Bartlett Quimby

Section 7.7

Compression Member Summary

Last Revised: 05/29/2023

Compressive strength is limited by:

• Material Strength
• General Buckling
• Local Buckling

Strength Limit States:

All strength limit states take the form:

The STRENGTH of a Column is computed by:

The nominal capacity of the column, P_n = F_n A_g

• F_e = p² E / (L_c/r)² = Euler Critical Buckling Stress

• L_c = KL = Effective Length. The choice of K will depend on how the demand side of the inequality was computed.

Slenderness Limit State (SCM E2)

This serviceability limit state is not binding, but a good suggestion:  (L_c/r) < 200 for members in place,  (L_c/r) < 300 in fabrication and transportation.

Computing Effective Length (SCM Commentary 7.2)

Principles of Mechanics are used to determine the effective length of columns. The effective length is a function of the overall member length, length between lateral braces, end support condition, and the arrangement of these factors relative to each principle axis. If Direct Analysis or other acceptable second order analysis is used, computing effective length is simplified by using an effective length coefficient, K, of 1.00.

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