Box Girder Stiffener Calculator

Design transverse and bearing stiffeners for box girders to prevent web buckling.

1. Box Girder Geometry

mm

mm

mm

mm

2. Loading Conditions

kN

kN

mm

Design Results

STIFFENER LAYOUT

Web Slenderness (h/t): 0
--
Transverse Stiffeners
Max Spacing: 0 mm
Dimensions: --
Bearing Stiffeners
Req. Area: 0 mm²
Dimensions: --
Checks against Shear Buckling & Crippling

Web Check

Checks h/t ratio against 200/√Fy limit. If exceeded, intermediate stiffeners are mandated.

Spacing

Spacing is optimized to ensure shear capacity exceeds the maximum shear force (V_max).

Bearing

Bearing stiffeners are sized to prevent web crippling under concentrated wheel loads.

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Understanding Box Girder Stiffeners

In deep box girders, the web plate is prone to buckling under shear loads and concentrated wheel loads. Stiffeners are welded plates that reinforce the web. This calculator helps you design both Transverse (Intermediate) Stiffeners and Bearing Stiffeners.

Inputs Explained

  • Web Depth (h) & Thickness (t_w): The dimensions of the main vertical plate of the girder. High h/t ratios increase buckling risk.
  • Max Shear Force (V): The maximum vertical shear force in the girder, usually near the supports.
  • Max Wheel Load (P): The concentrated load from the trolley wheels acting on the top flange.
  • Wheel Contact (N): The length of the wheel contact patch (or rail height + flange thickness distribution) used for crippling checks.

Outputs Explained

  • Web Slenderness (h/t): If this exceeds the limit (e.g., 200/√Fy), stiffeners are mandatory.
  • Transverse Stiffeners: Vertical plates spaced along the girder. The calculator provides the maximum allowable spacing and minimum dimensions.
  • Bearing Stiffeners: Reinforced sections under the wheel loads. The calculator provides the required cross-sectional area and dimensions.