S355JR and Q355B channels have identical fatigue properties, critical for dynamic-load applications (e.g., crane rails, highway bridges):
Fatigue Strength: Both have a fatigue limit of ~190 MPa at 2×10⁶ cycles (EN 1993-1-9, GB 50017-2017), meaning they withstand the same cyclic loads without failure.
Welded Joint Fatigue: Welded S355JR and Q355B joints have identical fatigue classes (FAT 90 for fillet welds), so no design changes are needed for welded connections.
Application Example: A UPE 200 S355JR channel in a Chinese factory crane rail supports the same 5 kN cyclic load (200 cycles/hour) as a GB C200x75x7 Q355B channel, with no difference in service life (20+ years).
This fatigue alignment ensures European channels perform reliably in dynamic GB applications, with no risk of premature failure.