Japanese Industrial Standard JIS G3192 (Hot-Rolled Steel Angles) defines unequal-angle steel dimensions with a "long leg (B) × short leg (b) × thickness (t)" format, tailored to Japan's seismic-resistant construction needs. Unequal angles under JIS G3192 have long legs (B) ranging from 40mm to 200mm, short legs (b) from 25mm to 125mm, and thicknesses (t) from 3mm to 19mm. Key examples include:
50×32×4mm: Long leg 50mm, short leg 32mm, thickness 4mm, weight 2.47 kg/m
75×50×5mm: Long leg 75mm, short leg 50mm, thickness 5mm, weight 4.72 kg/m
125×75×8mm: Long leg 125mm, short leg 75mm, thickness 8mm, weight 11.50 kg/m
200×125×12mm: Long leg 200mm, short leg 125mm, thickness 12mm, weight 23.10 kg/m
JIS G3192 specifies strict tolerances to ensure precision in seismic applications:
Leg length: ±1.0mm for legs ≤100mm, ±1.5mm for legs >100mm
Thickness: ±0.3mm for thicknesses ≤6mm, ±0.5mm for thicknesses >6mm
Length: ±5mm for standard lengths (6–12m), ±10mm for custom lengths (up to 20m)
Unlike EN or ASTM, JIS unequal angles often have slightly thicker webs (the inner corner) to enhance load-bearing capacity during earthquakes. These dimensions are used in Japanese construction projects (e.g., high-rise buildings, bridges) and exported to Southeast Asia, where JIS standards are recognized for reliability. Mills producing JIS unequal angles must adhere to regular inspections by the Japan Iron and Steel Federation (JISF) to maintain certification.