CIVILKITSengineering tools Read the basis
CivilKits/Calculators/Structural/Design/Eurocode/EN 1993-1-1 / section resistance

structural / design / eurocode 3

Eurocode 3 steel cross-section resistance.

Calculate a declared first-generation EN 1993-1-1 subset from user-supplied gross area, section moduli, shear area, yield strength, and selected class.

Classification and NDP warning

The selected class must come from an action-specific EN 1993-1-1 §5.5/Table 5.2 classification. Confirm γM0, steel grade/thickness, shear-buckling basis, and the National Annex before project use.

declared calculation basis

Section properties are inputs, not hidden assumptions.

This page uses EN 1993-1-1:2005 + AC:2009 + A1:2014. It accepts Classes 1–3 only, uses user-supplied gross properties, and reports independent axial, major-axis bending, and plastic-shear resistances.

Clauses and equations

For Classes 1–3 in uniform compression, EN 1993-1-1 §6.2.4, Expression 6.10:

AXIAL COMPRESSIONNc,Rd = A fy / γM0

The v1 tension output is explicitly the gross-section yield component from §6.2.3, Expression 6.6:

GROSS TENSION YIELDNt,gross,Rd = A fy / γM0

Full tension resistance can also be governed by net-section rupture at holes, §6.2.3, Expression 6.7:

NOT IMPLEMENTED IN V1Nt,Rd = min(A fy/γM0, 0.9Anetfu/γM2)

For major-axis bending, §6.2.5 uses:

BENDINGClass 1/2: My,Rd = Wpl,yfy/γM0  ·  Class 3: My,Rd = Wel,y,minfy/γM0

For shear without torsion, §6.2.6, Expression 6.18:

PLASTIC SHEARVpl,Rd = Avfy / (√3γM0)

A is gross area, Wpl,y is the plastic major-axis modulus, Wel,y,min is the governing elastic modulus, and Av is the applicable shear area.

What this page does not check

  • Section classification itself, Class 4 effective properties, or the EN 1993-1-5 effective-section method.
  • Net-section rupture, holes, connections, welds, shear lag, or connection-zone resistance.
  • Combined axial force and bending under §6.2.9, bending-plus-shear reduction under §6.2.8, or torsion.
  • Web shear buckling under §6.2.6(6) and EN 1993-1-5. The user must confirm that it does not govern.
  • Flexural buckling, torsional buckling, lateral-torsional buckling, member imperfections, fatigue, fire, seismic, execution, or robustness.