Fillet weld

About the program

Reference: NS-EN 1993-1-8:2005+NA:2009 – 4.5.3.2 Directional method

The program calculates fillet weld capacity according to clause 4.5.3.2 (directional method) in NS-EN 1993-1-8:2005+NA:2009.

Typical use case: Capacity check of fillet weld connections with combined shear force, normal force and moment.

Illustration of fillet weld with applied loads

Key formulas

Resultant stress

σopptr=σ⊥2+3⋅(τ⊥2+τ∥2)\sigma_{opptr} = \sqrt{\sigma_{\perp}^2 + 3 \cdot \left(\tau_{\perp}^2 + \tau_{\parallel}^2\right)}
σ⊥\sigma_{\perp}Normal stress perpendicular to the weld throat
τ⊥\tau_{\perp}Shear stress perpendicular to the weld longitudinal axis
τ∥\tau_{\parallel}Shear stress parallel to the weld longitudinal axis

Design capacity

σdim=fuβw⋅γM2\sigma_{dim} = \frac{f_u}{\beta_w \cdot \gamma_{M2}}
fuf_uNominal tensile strength
βw\beta_wCorrelation factor
γM2\gamma_{M2}Partial factor for welded connections

Inputs

  • Throat thickness, a (mm)
  • Weld length, leff (mm) and number of welds, n
  • Shear force, Vf (kN)
  • Normal force, Nf (kN) and moment, Mf (kNm)

Outputs

  • Resultant stress, σres (N/mm²)
  • Design capacity, σdim (N/mm²)
  • Utilization (%)
  • Normal stress condition, σ⊥ ≤ 0.9 · fu / γM2

Assumptions

  • Directional method – 4.5.3.2 in NS-EN 1993-1-8:2005+NA:2009
  • Rectangular weld cross-section with combined loading (V, N, M)
  • All welds in the group are assumed identical

Video coming soon.