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Distance between side-girt fly braces or wall bracing points, usually with K = 1.0.
Sway frames only. K′ = K·√(1 + ΣPlean/ΣPframe) (Yura), valid when the frame columns of the storey are similar.
AISC Commentary Table C-A-7.1 (same cases in ECP). Recommended values allow for joints that are never perfectly fixed.
Computed live by this page's own solvers when it opens. Pass = within 0.5 % of exact theory, or within ±0.01 of values read from the AISC alignment charts.
To reproduce a case in SAP2000: model the column as one frame member (non-prismatic section for tapered), add rotational springs k at both ends using the values printed in the worked solution, restrain the base laterally (and the top too for a braced frame), apply a 1 kN axial load and run a Buckling load case. The first buckling factor is Pcr in kN.
Prismatic columns: K from the exact alignment-chart equations (AISC Commentary C-A-7-1 / C-A-7-2, same charts used by ECP), solved numerically. Tapered columns: elastic finite-element buckling (60 elements) with joint springs k = 6EIc/(LcG) for sway or 2EIc/(LcG) for braced frames, which reproduces the chart equations exactly for prismatic members; K is referred to the smaller end. Beam far-end factors m follow AISC Commentary Appendix 7.
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