Web–flange fillet weld · EN 1993-1-8 §4.5
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Weld verification · EN 1993-1-8 §4.5

Weld verification of the web-flange connection in a built-up I-section

This tool verifies the web-to-flange fillet weld in a built-up I-section subjected to shear force, bending moment and axial force, in accordance with the simplified method of EN 1993-1-8 §4.5.3.3.

The verification is performed against the longitudinal shear flow acting at the web-to-flange interface, evaluated assuming linear elastic section behaviour using Jourawsky's formula. By equilibrium, only the shear stress component parallel to the weld axis acts on the weld throat plane.

Enter the section geometry, throat thickness a, material properties and design actions to obtain the complete verification, including all intermediate calculation steps. The tool also exports a PDF report suitable for project documentation.

Shear flow and Jourawsky's formula
For a built-up I-section subject to shear force VEd, the shear flow at the web–to-flange interface is evaluated as: q = VEd · S / Iy, where S is the first moment of area of the flange about the neutral axis and Iy is the second moment of area of the entire section. The resulting shear flow per unit length [N/mm] is shared between the two fillet welds on each side of the web.

Fillet weld geometry (EN 1993-1-8 §4.3)
The effective throat thickness a is defined as the minimum distance from the fusion plane to the weld surface. The effective length is the total length reduced by twice the throat: leff = l − 2a. The shear flow acts parallel to the weld axis, generating only the shear component τ∥ on the throat plane.

Simplified method §4.5.3.3
The simplified method assumes that the fillet weld resistance equals Fw,Rd = fvw,d · a regardless of weld orientation, where a is the throat size and fvw,d = fu / (√3 · βw · γM2) is the design shear strength of the weld. For a longitudinal shear connection weld, the force per unit length on the weld is compared to Fw,Rd. The correlation factor βw depends on steel grade (S235: 0.80 — S275: 0.85 — S355: 0.90 — S420/S460: 1.00) per EN 1993-1-8 Tab. 4.1.

Normative references: EN 1993-1-8:2005 §4.3, §4.5.3.3

☷ Section library
Geometry
Weld & Material
Check EN 1993-1-8
Formulas & Notes
IPE / HEA Built-up I-section geometry
mm
mm
mm
mm
CALC mm
CALC —
hw = h − 2·tf  |  Welded section — no web-flange fillet radius
NNotation
ATotal area
ISecond moment of area
SfFirst moment of area – flange
WelElastic section modulus
efFlange arm from N.A.
AfFlange area = bf·tf
⊞Cross-section diagram
—
∑Section properties
Format
Decimals 2
§4.5 Fillet weld — geometric parameters
mm
CALC mm
amin = max(3 mm ; 0.7·√tmin)  |  amax = 0.7·tmin — EN 1993-1-8 §4.5.2
FDesign actions
kN
⚙Material — base steel (EN 10025-2)
AUTO mm
—
MPa
—
—
CALC MPa
⊞Fillet weld detail
—
∑Weld resistance parameters
fvw,d = fu / (√3 · βw · γM2)  |  Fw,Rd = fvw,d · a · ns  [N/mm per unit length]
§4.5 — Jourawsky Shear flow qEd
qEd = VEd · Sf / I  (Jourawsky formula)  — EN 1993-1-8 §4.5
§4.5.3.3 Weld resistance Fw,Rd
fvw,d = fu / (√3·βw·γM2)  |  Fw,Rd = fvw,d · a · ns
§4.5.2 Throat size limits a
CHECK qEd ≤ Fw,Rd
Check per unit length of weld — EN 1993-1-8 §4.5.3.3
DETAIL Calculation steps
▣Summary — optimal throat

Export verification report to PDF (with figures)

⊞Section and weld diagram
b_f × t_f t_w b_f × t_f N.A. h e_f a fillet weld flange
aWeld throat size (height of the inscribed isosceles triangle)
z = a·√2Weld leg (dimension marked in workshop)
efFlange centroid distance from N.A. = hw/2 + tf/2
qShear flow — Jourawsky
qEd = VEd · Sf / I Sf = Af · ef = bf · tf · (hw/2 + tf/2) I = tw·hw³/12 + 2·(bf·tf³/12 + Af·ef²)

qEd [N/mm] is the shear flow that the weld must transfer per unit length. It is derived from the equilibrium of the flange subjected to shear VEd (Jourawsky's formula).

§4.5.3.3Fillet weld resistance
fvw,d = fu / (√3 · βw · γM2) Fw,Rd = fvw,d · a · ns  [N/mm]
fuUltimate tensile strength of the weaker base plate (EN 10025-2, thickness-dependent)
βwCorrelation factor Tab. 4.1 EN 1993-1-8
γM2Partial factor = 1.25 (recommended value)
nsNo. of welds per joint (1 single, 2 double)
§4.5.2Throat size limits
amin = max(3 mm ; 0.7 · √tmin) amax = 0.7 · tmin

tmin = spessore minore dei due pezzi da saldare (anima o flange). La gola minima garantisce fusione adeguata; la gola massima evita distorsioni e cricche.

βwCorrelation factor — Tab. 4.1 EN 1993-1-8
S235βw = 0.80
S275βw = 0.85
S355βw = 0.90
S420βw = 1.00
S460βw = 1.00
Disclaimer and scope of application

The verification covers exclusively the web-to-flange fillet weld in built-up I-sections subjected to in-plane internal forces (V, M, N). The following are not considered: butt welds, welds subjected to out-of-plane forces, fatigue effects, or web stability checks according to EN 1993-1-5.

Results must always be verified by a qualified structural engineer before use in a real project. This tool is provided as a calculation aid and does not replace the professional responsibility of the designer.