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 classification (5.5 / Table 5.2): Class 1-4 section classes are assigned by section family and active stress state.
- Class 4 effective sections (EN 1993-1-5): Supported flat-plate Class 4 paths use effective properties; CHS shell buckling is outside scope.
- Section resistance (6.2.3-6.2.10): Tension, compression, bending, shear, shear-bending, and N+M section checks use the reported clause row.
- Member buckling (6.3.1 / 6.3.1.4): Flexural and supported torsional or flexural-torsional compression buckling checks are reported separately.
- LTB (6.3.2.1(3) / 6.3.2.2 / 6.3.2.3): LTB resistance uses the general or modified I/H reduction method according to the section family.
- Combined stability and torsion (6.3.3 / 6.2.6(4) / 6.2.7): Annex B stability interaction and closed-hollow-section torsion rows are reported where applicable.
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
- Tension rupture under 6.2.3 uses gross section area because bolt-hole deductions are not inferred. Check connection-region net sections separately.
- 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).
- EN 1993-1-5 local transverse force, patch loading, web bearing, web buckling, end-post, and transverse-stiffener checks are not performed or derived from point loads, reactions, or connection forces. Check support bearing and concentrated load introduction regions separately.
- Angle sections: torsional-flexural buckling (6.3.1.4) not checked: doubly-asymmetric sections require a separate formulation not provided in EC3.
- CHS Class 4 is not designed: circular hollow sections beyond the EN 1993-1-1 Table 5.2 Class 3 limit require EN 1993-1-6 shell buckling, which is outside this member engine scope.
- 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, closed hollow sections (RHS/SHS/CHS) use the 6.2.6(4) torsional shear stress check when a torsional section modulus is supplied or derivable; 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 →