The flange width (b) of HEB steel is critical for resisting lateral forces in tall structures:
Moment of Inertia (Iᵧ): Wider flanges increase Iᵧ, reducing lateral deflection. A HEB 400 (b=400mm) has 35% higher Iᵧ than HEB 300 (b=300mm), making it suitable for buildings over 150m tall.
Example: The Burj Khalifa uses HEB 700 with 350mm flanges to limit wind - induced sway to 1.5m during 160km/h gusts.
Connection Strength: Broader flanges provide more surface area for beam - to - column connections. A HEB 300 flange (300mm wide) can accommodate 8 M24 bolts per side, increasing joint rigidity by 25% compared to narrower flanges.
Slenderness Ratio: Engineers use flange width to maintain a slenderness ratio (λ = L/r) < 150 per EN 1993 - 1 - 1. For a 50m - tall column, a HEB 500 (b=500mm) reduces λ by 20% versus a narrower profile, minimizing buckling risk.
In seismic zones, wider flanges also improve torsional resistance, helping structures absorb energy during earthquakes by allowing controlled plastic deformation.
