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Castellated Beam Web Opening Net-Section Shear Calculator

Check the net-section shear capacity of a castellated/cellular steel beam at a web opening.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Net-section shear capacity

331.2 kN

Check your inputs

This is a basic net-section shear screening check ONLY. Vierendeel bending and web-post buckling at the opening — often the governing failure modes for castellated/cellular beams — are NOT evaluated here and require specialist software (AISC Design Guide 31, SCI P100, or FE analysis).

Net web area at opening
1600 mm²

With the figures above, the net-section shear capacity comes to 331 kN. The method behind this is well established, though site conditions and material batches will move it somewhat. This is calculated for United States and cites IRC 2024. Building in another market? Change the selector above so the units and code reference follow.

Add the equipment this sizes

This result is a specification — 331.2 kN — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Basic net-section shear check: Vn = 0.6×Fy×Aw, where Aw = (beam depth − opening height) × web thickness. This is a starting-point screening check only — full castellated beam design also requires Vierendeel bending and web-post buckling checks (AISC Design Guide 31 / SCI P100), which are geometry-dependent, multi-step procedures with no single general formula and are NOT covered by this calculator.

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

What failure modes does this calculator check?
Only basic net-section shear yielding at the reduced web area beside the opening (Vn = 0.6×Fy×Aw). It does not check Vierendeel bending of the web posts around the opening or web-post buckling — both of which frequently govern the actual capacity of castellated/cellular beams.
Why isn't Vierendeel bending or web-post buckling included?
Those checks are geometry-dependent, multi-step procedures (covered by AISC Design Guide 31 or SCI P100) with no single general formula — they depend on opening spacing, shape, web-post width, and other section-specific factors that this simple screening calculator does not capture.
Is passing this check enough to confirm the beam is adequate?
No — this is a starting-point screening check only. A full castellated/cellular beam design requires the additional Vierendeel bending and web-post buckling checks from AISC Design Guide 31 or SCI P100, typically performed with specialist software.