Connection Screen — Column Slenderness (KL/r)
Column Slenderness (KL/r) — a screening-level structural check.
Slenderness is the column story in one ratio: below ~50 the steel's strength rules, above ~120 Euler's geometry does and capacity falls with the square. The erection-stage trap: a column unbraced at FULL height during erection has a different r-governing axis than the finished frame assumed.
Formula
Note: Screening only — NOT a connection design. All capacities must be verified by a licensed engineer against the governing code, including the limit states this simplified check omits.
Column Slenderness (KL/r) — a screening-level structural check. A free structural steel delivery & erection tool — no sign-up, no upload, instant results in your browser.
About Connection Screen — Column Slenderness (KL/r)
Connection Screen — Column Slenderness (KL/r) computes the governing relationship λ = K·L/r — the only number Euler needs live as you type. Slenderness is the column story in one ratio: below ~50 the steel's strength rules, above ~120 Euler's geometry does and capacity falls with the square. The erection-stage trap: a column unbraced at FULL height during erection has a different r-governing axis than the finished frame assumed. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.
How to use Connection Screen — Column Slenderness (KL/r)
- 1Enter your values — Effective length K, Unbraced length, Governing radius of gyration (sensible defaults are pre-filled).
- 2Read the live results: KL/r.
- 3Check the "with your numbers" line to see λ = K·L/r — the only number Euler needs substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Connection Screen — Column Slenderness (KL/r)?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula λ = K·L/r — the only number Euler needs with authoritative sources cited on the page (AISC 360 — Specification for Structural Steel Buildings; RCSC — Specification for Structural Joints Using High-Strength Bolts)
- ✓Slenderness is the column story in one ratio: below ~50 the steel's strength rules, above ~120 Euler's geometry does and capacity falls with the square.
- ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use
Frequently asked questions
What formula does the connection screen — column slenderness (kl/r) use?+
It evaluates λ = K·L/r — the only number Euler needs, exactly as published. Sources: AISC 360 — Specification for Structural Steel Buildings; RCSC — Specification for Structural Joints Using High-Strength Bolts. The substituted worked example on the page lets you verify every step against the textbook.
How should I read the result — and how far can I trust it?+
Slenderness is the column story in one ratio: below ~50 the steel's strength rules, above ~120 Euler's geometry does and capacity falls with the square. Screening only — NOT a connection design. All capacities must be verified by a licensed engineer against the governing code, including the limit states this simplified check omits.
When is this calculator the right tool for the job?+
Column Slenderness (KL/r). The erection-stage trap: a column unbraced at FULL height during erection has a different r-governing axis than the finished frame assumed. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Does it support both metric and imperial units?+
Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.
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