Fatigue performance assessment of the steel truss gusset plate-to-crossbeam joint considering welding residual stress

As a critical load‑transfer component of steel truss bridges, the integral gusset plate‑to‑crossbeam joint faces prominent fatigue risks induced by welding residual stresses in practical engineering. Therefore, this study investigates the spatial distribution of welding residual stress in its fatigue‑prone detail and evaluates its influence on fatigue performance. Based on the damage mechanics method, a fatigue life assessment framework is established. This framework comprehensively considers the effects of the welding residual stress field on both fatigue life and crack location. Utilizing this framework, the fatigue performance of the joint is quantified under three conditions: without welding residual stress, with welding residual stress, and after post-weld heat treatment. The results indicate that the initial welding residual stress reaches the yield strength of the steel. PWHT significantly reduces the residual stress level, corresponding to a stress relief ratio exceeding 71–80%. Under the same fatigue load amplitude and structural constraints, the presence of welding residual stress causes the location of fatigue crack initiation to shift from above the weld access hole towards the sides, thereby altering the failure path of this fatigue-prone detail. The calculation results show that the fatigue life considering PWHT is 2.1 × 10⁶ cycles, which meets the design requirements. Furthermore, welding residual stress reduces the fatigue life by 39.6%, while PWHT increases it by 23.6%.