Check the resistance of a steel web to transverse (concentrated) forces per EN 1993-1-5 §6. Covers load types a (between stiffeners), b (one flange, near end stiff bearing), and c (one flange, near unstiffened end). Computes kF, Fcr, ℓy, λ̄F, χF, FRd and the optional interaction check with concurrent bending moment (§7.2). IPE, HEA, HEB, UB. S235–S460.
Section Parameters
Length of stiff bearing: width of load distribution over flange. For a wheel: 0. For a stiffener: equal to stiffener width. Min 0.
Distance between transverse stiffeners. Used for k_F. For beams without intermediate stiffeners, use span length.
For load types b/c: distance from load centroid to the nearest end of the member. Leave 0 for type a.
Concurrent bending moment for §7.2 interaction check. Leave 0 to skip interaction.
What is web bearing and buckling under transverse forces?
When a concentrated load or reaction force is applied through the flange, it is distributed into the web over an effective length L_eff. The web must resist this without crippling (yield at the load point — bearing) or buckling (elastic instability of the web under the concentrated load). EN 1993-1-5 §6 gives a unified formula F_Rd = f_yw · L_eff · t_w / γ_M1 that covers both failure modes via the slenderness factor χ_F.
What are load types a, b, and c?
Type a (Fig. 6.1a): the load is applied between two transverse stiffeners (or end plates), supported through both flanges — most common in mid-span or interior panels. Type b (Fig. 6.1b): the load is on one flange near a stiffener or end with a stiff bearing — e.g. a crane wheel near an end plate. Type c (Fig. 6.1c): the load is on one flange at or near an unstiffened end — the most onerous case, giving k_F = 2.0.
How is the effective loaded length ℓ_y computed?
ℓ_y is the length of the web over which the transverse force is assumed to spread. Per Eq. 6.10–6.13: ℓ_y = s_s + 2·t_f·(1 + √(m₁ + m₂)) when m₂ > 0 (slender web), or ℓ_y = s_s + 2·t_f·(1 + √m₁) when m₂ = 0 (stocky). Here m₁ = f_yf·b_f / (f_yw·t_w) accounts for flange-to-web yield strength spread, and m₂ = 0.02·(h_w/t_f)² penalises slender webs.
What is the buckling coefficient k_F?
k_F is derived from Figure 6.1 and depends on load type and the panel aspect ratio h_w/a. For Type a: k_F = 6 + 2·(h_w/a)². For Type b: k_F = 3.5 + 2·(h_w/a)². For Type c: k_F = 2.0 (conservative constant for unstiffened ends). Higher k_F means more resistance — a stocky panel between close stiffeners benefits substantially.
What is the §7.2 interaction check?
When a beam is simultaneously loaded by a transverse force F_Ed and a bending moment M_Ed (and/or axial N_Ed), EN 1993-1-5 §7.2 requires: η₂ + 0.8·η₁ ≤ 1.4, where η₂ = F_Ed/F_Rd is the patch loading utilisation and η₁ = M_Ed/M_Rd is the bending utilisation (M_Rd = W_pl·f_y/γ_M0 for a Class 1/2 section). This interaction is most critical for crane runway girders and plate girders under wheel loads.
Is γ_M1 = 1.0 for all national annexes?
Yes for the EN, NL (NEN-EN 1993-1-5/NB), DE (DIN EN 1993-1-5/NA), and BE annexes. The UK NA also retained 1.0. Use the National Annex selector to apply the correct value if your project differs.