American H-beams (W-shapes) have web thicknesses that are slightly thicker than their GB counterparts, but this difference enhances shear capacity without compromising substitution:
Web Thickness Comparisons:
W8x48 A992 (web thickness 0.315 inches ≈8.0 mm) vs. HW 200x200 Q355B (8.0 mm)-identical, ensuring the same shear capacity (critical for resisting wind or seismic loads).
W10x49 A992 (0.345 inches ≈8.8 mm) vs. HM 250x118 Q355B (6.5 mm)-A992's thicker web provides 35% higher shear capacity, making it suitable for applications where HM's thinner web may be insufficient (e.g., high-wind zones).
W6x25 A36 (0.320 inches ≈8.1 mm) vs. HN 160x88 Q235B (5.0 mm)-A36's thicker web enhances durability in light-load applications, reducing the risk of web buckling.
Impact on Shear Design: Shear capacity is calculated using web thickness (V = 0.6FyAw, where Aw = web area). American W-shapes' thicker webs provide higher shear capacity, which can be leveraged to reduce the number of beams or increase span lengths. For example, a W10x49 A992 beam can span 6 meters without additional shear reinforcement, while a HM 250x118 Q355B beam may require stirrups for the same span.
Fabrication Compatibility: Thicker webs require slightly longer drill bits for bolt holes, but this is a minor adjustment. Chinese manufacturers commonly use drill bits with lengths up to 150 mm, which accommodate American web thicknesses (up to 0.5 inches ≈12.7 mm) without issue.
The thicker web of American H-beams is a beneficial difference, as it enhances shear capacity and durability-making substitution even more reliable for demanding applications.