Effectiveness and durability evaluation of cold reinforcement for Distortion-induced fatigue in steel bridges

Full-scale fatigue tests and numerical damage simulation were performed to evaluate the effectiveness and durability of two cold reinforcement methods (bonding steel angle, hybrid bonding and bolting steel angle), under the action of fatigue loads and environmental effects. Fatigue test results after reinforcement and the further long-term durability test results including both internal and exterior girders under different environmental effects indicate that two cold reinforcement techniques are highly effective and durable to arrest distortion-induced fatigue cracking and decrease out-of-plane distortion. Numerical fracture evaluation considering both durability and fatigue damage of cold reinforcement joints shows stress intensity factor (SIF) at fatigue crack tips reduced below threshold, demonstrating that cracks would not propagate, consistent with test results. The innovative hybrid cold bonding and bolting steel angles reinforcement method is recommended, because it can not only avoid traffic disruption and angle falling, but also arrest fatigue crack growth effectively without drilling hole damage at girder flanges.