Whitmore Effective Width Method

The Whitmore section accounts for stress dispersion at 30° from the bolted or welded connection:

L_eff = L_weld + 2 × L_disp × tan(30°)

Where L_weld is the weld length at the brace end and L_disp is the distance from the connection face to the critical cross-section of the gusset.

The Whitmore width gives the effective gusset section for tension yielding check:

N_t,Rd = L_eff × t_g × f_y / γ_M0

Where t_g = gusset plate thickness.

Design Checks

1. Tension Yielding (Gross Section)

N_t,Rd = L_eff × t_g × f_y / γ_M0

2. Tension Rupture (Net Section at Bolt Holes)

N_u,Rd = A_net × f_u / γ_M2

For bolted brace connections, net area = gross area minus bolt hole area.

3. Block Shear — EN 1993-1-8 Clause 3.10.2

V_eff,Rd = f_u × A_nt / γ_M2 + (1/√3) × f_y × A_nv / γ_M0

Where A_nt = net area in tension, A_nv = net area in shear.

4. Gusset Plate Buckling

For gusset plates in compression, check per EN 1993-1-1 Clause 6.3.1:

N_b,Rd = χ × A × f_y / γ_M1

Use buckling curve c (α = 0.49) for gusset plates. The effective length may be taken as 0.65 × L (rigid frame) or 1.0 × L (simple support), where L is the free edge length.

5. Weld Design

Fillet welds between brace and gusset per Clause 4.5:

• Total weld capacity ≥ applied brace force
• Weld return at the gusset edge (25-50 mm each side) for ductility

Worked Example — CHS 139.7×8 Brace, Gusset Plate

Tension Yielding Check

Block Shear Check

Gusset Buckling Check

Weld Design

Note: For the full brace capacity to be developed, large welds or longer weld length is required. In practice, the connection detail may use a slot-and-plate or doubler plate to reduce weld demand.

Minimum Gusset Plate Thickness

Per EN 1993-1-8 and common practice:

Frequently Asked Questions

What is the Whitmore section and why is it used for gusset plate design?

The Whitmore section is the effective width of the gusset plate through which the brace force is distributed, assuming a 30° stress dispersion angle from the connection. It accounts for the non-uniform stress distribution across the gusset plate. The Whitmore width L_eff = L_connection + 2 × L_disp × tan(30°), where L_connection is the connection length and L_disp is the distance from the connection to the critical section.

When should gusset plate buckling be checked?

Gusset plate buckling must be checked when the brace is in compression. Per EN 1993-1-8, the gusset is treated as a compression element. The buckling check considers the free edge of the gusset as a column. For gussets with stiffened edges (folded gusset, stiffeners), the buckling capacity increases significantly. For braces with tension-only design (e.g., cross-bracing), buckling of the gusset in compression is not critical.

Related Pages

• Brace Connection — Brace connection per EN 1993-1-8
• Shear Tab Connection — Fin plate per EN 1993-1-8
• End Plate Connection — Moment connection
• Column Design — Compression per EN 1993-1-1
• All European References

Educational reference only. Design per EN 1993-1-8:2005. Whitmore method per AISC/SCI guidance. Verify gusset dimensions against actual brace angle and connection geometry. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent verification.

Design Resources

Calculator tools

• Bolted Connection Calculator
• Weld Capacity Calculator
• End Plate Moment Connection Calculator
• Fin Plate Shear Connection Calculator
• Gusset Plate Calculator

Design guides

• Bolted Connection Worked Example
• Bolted Connection Checklist
• Steel Connection Calculator Guide
• Weld Design Checklist
• EN 1993-1-8 Bolted Connection Worked Example

Reference pages

• EU Shear Tab
• UK Moment Connection