Ideal elastic bifurcation — not design resistance
Elastic Euler Column Buckling Check
Evaluate global flexural buckling about the weakest axis only after checking that Euler’s trial stress remains within a supplied verified elastic range.
Elastic applicability result
NISTIR 6779, Appendix D.5 gives Euler’s formula for long slender beams/columns, defines I as the least area moment of inertia and Le as the effective length, and identifies Le=L for pivoted ends and Le=L/2 for fixed ends.
MIT Mechanics and Materials II, “Elastic Buckling of Long Slender Columns” derives the same effective-length form and relates Le=KL to ideal end fixity. Real frame restraint must come from the applicable structural model/code, not from a generic dropdown.
The gate follows algebraically by setting the Euler stress equal to the user-supplied maximum elastic stress. It is a necessary check for this ideal elastic formula, not a complete code classification or proof of safety.
If rejected: the calculator deliberately suppresses Pcr and σcr. Use the applicable material/structural design standard and check inelastic, local and coupled buckling instead of treating an out-of-range Euler number as capacity.
