Fillet Weld Check

Perform a quick stress check for a weld following Eurocode 3.

Geometry

Length L (mm)

Thickness t (mm)

Throat thickness a (mm)

Weld length reduction

Yes No

Apply β_red (-)

Loads

F_x,Ed (kN)

F_y,Ed (kN)

F_z,Ed (kN)

M_x,Ed (kNm)

M_y,Ed (kNm)

M_z,Ed (kNm)

Material

Yield stress (N/mm²)

Ultimate tensile stress (N/mm²)

β_W (-)

γ_M2 (-)

Stress results

Stress direction .	Quantity (N/mm²)
τ_//	-
τ_⟂	-
σ_⟂	-

Stress type	Occuring stress (N/mm²)	Allowable stress (N/mm²)	Unity check
σ_⟂	-	-	-
σ_VM	-	-	-

Legend

Parameter name	Symbol	Unit	Info text
Weld length	L	mm	Overall length of the fillet weld. The effective length used in calculations may be subject to reductions (e.g., for end craters or long weld effects).
Plate thickness	t	mm	Thickness of the plates being joined. A minimum plate thickness of 4 mm is recommended.
Throat thickness	a	mm	Effective throat thickness of the weld. This is the critical dimension for strength calculations (min. 3mm is recommended). For equal leg 90° welds, a ≈ 0.707z (where z is leg length).
Length reduction factor	β_red	-	Factor applied to account for non-uniform stress distribution in long welds (e.g., β_Lw1 for connections > 150a or β_Lw2 for welds > 1.7m on transverse stiffeners). Applied if weld length reduction is specified.
Applied forces	F_x,Ed, F_y,Ed, F_z,Ed	kN	Design force components along the defined X, Y, Z input axes. These are resolved into normal (σ⊥) and shear (τ⊥, τ∥) stresses on the weld throat.
Applied moments	M_x,Ed, M_y,Ed, M_z,Ed	kNm	Design moment components about the defined X, Y, Z input axes. These are resolved into normal (σ⊥) and shear (τ⊥, τ∥) stresses on the weld throat.
Yield stress	f_y	N/mm²	Nominal yield strength of the weaker of the two parent materials being joined.
Ultimate tensile stress	f_u	N/mm²	Nominal ultimate tensile strength of the weaker parent material. This value is critical for determining the weld's design strength.
Correlation factor	β_W	-	Correlation factor for fillet welds, dependent on the steel grade of the parent material (e.g., S235: 0.8, S275: 0.85, S355: 0.9). Refer to EN 1993-1-8, Table 4.1.
Partial safety factor	γ_M2	-	Partial safety factor for the resistance of welds. Typically 1.25 according to EN 1993-1-8, but always verify the value specified in the relevant National Annex.
Parallel shear stress	τ_∥	N/mm²	The calculated shear stress component in the weld's throat plane acting parallel to the longitudinal axis of the weld.
Perpendicular shear stress	τ_⊥	N/mm²	The calculated shear stress component in the weld's throat plane acting perpendicular to the longitudinal axis of the weld.
Perpendicular normal stress	σ_⊥	N/mm²	The calculated normal stress component acting perpendicular to the plane of the weld's throat.
Design weld resistance (combined stress)	-	-	The weld must satisfy the condition: √(σ_⊥² + 3(τ_⊥² + τ_∥²)) ≤ f_u / (β_Wγ_M2). This is the primary check for combined stresses according to EN 1993-1-8.
Design weld resistance (normal stress limit)	-	-	The normal stress perpendicular to the throat must also satisfy: σ_⊥ ≤ 0.9 f_u / γ_M2, according to EN 1993-1-8.
Unity check	UC	-	The ratio of the calculated design stress (or combination of stresses) to the design resistance. A value less than or equal to 1.0 indicates that the weld design is acceptable under the given loads.