BS EN 1993-1-1 has no crane-specific provisions of its own at all — the true governing document is EN 1991-3, with its own detailed dynamic factors for hoisting, travelling and skewing, far more nuanced than the single flat impact percentage this module applies by analogy instead.
Every check above runs automatically inside the Structyze Gantry Girder module — this particular module is part of the full desktop catalogue rather than the free browser trial, since the trial only carries a curated flagship set. You can still try the free trial modules right now to see the same calculation style in action on RCC Beam, Column, Slab and a handful of others.
The Example We'll Use
- Span 6 m
- Section 450 × 200 × 20 × 12 mm
- Maximum static wheel load 100 kN
- Vertical impact factor 25%, lateral surge 10%
- Material S235, fy = 235 MPa
Working Through It
Section classification finds both flange (5.0 against 9.0ϵ) and web (34.2 against 72.0ϵ) Class 1. Using EN 1990's generic 1.5 variable-action factor by analogy (not EN 1991-3's own crane-specific φ1–φ7 factors): WEd = 1.5(100)(1.25) = 187.5 kN, SEd = 1.5(100)(0.10) = 15 kN.
Design moments: MEd,z = 281.25 kN·m, MEd,y = 22.5 kN·m. Moment resistances, using S235's lower reference yield stress: Mc,Rd,z = Wplfy/γM0 ≈ 522.7 kN·m, Mc,Rd,y ≈ 97.47 kN·m.
What Governs, and Why
Biaxial bending governs at utilisation 0.769 (281.25/522.7 + 22.5/97.47 = 0.538 + 0.231) — noticeably tighter than this series' AISC 360 companion volume's identical-geometry example (utilisation 0.621). S235's lower reference yield stress (235 MPa versus 345 MPa) shrinks both moment resistances proportionally while the applied moments stay fixed by geometry and load. A direct illustration of how material grade selection alone can move a design from comfortable to tight without changing a single dimension.
Where Structyze Takes Over
Every check above runs automatically inside the Structyze Gantry Girder module — this particular module is part of the full desktop catalogue rather than the free browser trial, since the trial only carries a curated flagship set. You can still try the free trial modules right now to see the same calculation style in action on RCC Beam, Column, Slab and a handful of others.
For Gantry Girder and the rest of the full catalogue — 80+ components across RCC, Steel, Composite, Timber, Masonry and more, across 20+ design codes — buy the full Structyze desktop app or see everything it does on the Software page.
Quick FAQ
Why does this module use EN 1990's factor instead of EN 1991-3's own crane factors?
This is a disclosed simplification: EN 1991-3 ('Actions induced by cranes and machinery') defines dynamic factors φ1 through φ7 for hoisting, travelling and skewing effects, materially more detailed than a single flat impact percentage — but implementing that full framework is a bigger undertaking than this module's scope. Applying EN 1990's generic 1.5 factor by analogy gives a reasonable approximation, worth knowing before using this for an actual crane installation design submission.
Why does material grade alone shift this design from comfortable to tight?
Both moment resistances scale and proportionally with fy — S235 at 235 MPa versus a higher-strength grade like S355 at 355 MPa would give roughly 51% more capacity in both axes simultaneously, for the identical section dimensions. The applied moments, driven purely by geometry and load, don't change at all with grade, so the entire margin shift comes from the material choice.
Final Thoughts
Comparing this gantry girder's S235 result against the identical geometry under a higher-strength material elsewhere in this series makes material grade selection's real cost concrete — the same steel shape, a measurably different margin, purely from the grade stamped on the mill certificate.