Eurocode 3 Structural Steel Design
Design structural steel members according to EN 1993-1-1 standards. Our engine automates section classification and stability checks for any loading scenario.
Design Check Overview
EC3 categorizes sections into Classes 1–4 based on width-to-thickness ratios. This is critical for determining whether a section can reach its full plastic capacity or if local buckling will limit the design. Partial safety factors (γM0, γM1) provide resistance reduction margins, with values set by each country's National Annex.
Fabrication methods (rolled vs. welded) affect residual stresses, which in turn determine which EC3 buckling curve (a0, a, b, c, or d) is used for stability checks.
Clause Compliance Coverage:
- Section Resistance (6.2): Checks for tension, compression, bending, and shear interaction.
- Flexural & Torsional-Flexural Buckling (6.3.1): Flexural buckling per 6.3.1.1 with Table 6.2 curves. Torsional-flexural buckling per 6.3.1.4 for I-shapes, channels, and tees.
- LTB Resistance (6.3.2): Lateral-Torsional Buckling per clause 6.3.2.3 (rolled section method, Table 6.5) with f-factor correction.
- Interaction (6.3.3): Combined stability under axial force and biaxial bending using Annex B (Method 2) interaction factors. User-overridable Cmy, Cmz, CmLT equivalent uniform moment factors.
Supported Section Types
I/H Sections - IPE, HEA, HEB, UKB, UKC
Channels - UPN, UAP, PFC
Tees - UBT, UCT
RHS / SHS
CHS
Angles - EA, UA
Current Limitations
- Net section area (Anet) uses gross area — bolt hole deductions are not applied to tension rupture checks.
- Single member analysis only — no automatic frame buckling analysis or system-level effects.
- No connection design (EN 1993-1-8), no fire design (EN 1993-1-2), and no fatigue checks (EN 1993-1-9).
- Angle sections: torsional-flexural buckling (6.3.1.4) not checked — doubly-asymmetric sections require a separate formulation not provided in EC3.
- The calculator assumes the default section orientation shown in the preview. Major and minor axis inputs are relative to that orientation. Rotated or sideways mono-symmetric members, such as channels, tees, and angles, should be checked in the FEA workflow.
- Torsion is not an input in the standalone calculator. In the FEA tool, torsion (6.2.7) is checked for closed hollow sections (RHS/CHS) only — warping torsion for open sections is not performed.
- Partial safety factors (γM) must be verified against the relevant National Annex.
Benchmarks: 126 independent test cases, 0.43% average difference
Full Documentation →