Effective Length Factor
Figure 1: Shows how the effective length factor, the curvature, and the capacity of the member, vary depending upon the stiffness of the supports

Effective Length (K) Factor Explained:

The K factor approximates the length that a column (steel column's, concrete column's, aluminum column's, etc. all use the effective length factor) actually buckles. The effective length can be longer, shorter, or exactly the actual length depending on the rigidity of the supports. In practice, if the K factor is below 1.0 then the structure is braced (the structure has a greater ability to deal with any lateral forces) and if the structure is above 1.0 then the structure is unbraced (the structure has a lesser ability to deal with any lateral forces).

Steel and Aluminum Effective Length (K) Factor

The effective length factors for a majority of structural members[1] are detailed below.

k factor for steel columns

This factor is used in the following pages:

Concrete Effective Length Factor

The effective length factors for concrete columns are determined by the ''Jackson & Mooreland Alignment Charts[2] are detailed below.

k factor for concrete columns

This factor is used in the following pages:

Wood Effective Length Factor

The wood effective length factor has been previously discussed here?.

References:

  1. American Instituted of Steel Construction (AISC), "Manual of Steel Construction (8th edition)", 1980
    • Found in Table C1.8.1
  2. American Concrete Institute, "Building Code Requirements for Structural Concrete (ACI 318-05)", 2005
    • Found in Section R10.12.1

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