Web thickness (tw) is a critical factor in H-beam load-bearing capacity for tall buildings:
Shear Resistance: The web resists vertical shear forces. Thicker webs (e.g., 10mm vs. 6mm in a 300mm-height beam) increase shear capacity by 30%, essential for transferring loads from floors to columns in skyscrapers. For a 50-story building, optimized web thickness can reduce the number of beams by 15%, saving material costs.
Buckling Resistance: In slender columns, a thicker web delays lateral-torsional buckling under compressive loads. Standards like AISC 360 specify minimum web thicknesses based on slenderness ratios; for example, a 600mm-height column in a seismic zone requires a 12mm web to meet buckling safety factors.
Fire Performance: Thicker webs retain strength longer at high temperatures. A 8mm web in a fire-rated beam (120-minute rating) maintains 70% of its yield strength at 600°C, compared to 50% for a 5mm web, critical for evacuation time in tall structures.
Engineers use finite element analysis to optimize web thickness, balancing safety, cost, and architectural requirements, ensuring H-beams excel in iconic high-rises like Singapore's Guoco Tower.
