The weathering steel has a good atmospheric corrosion resistance due to dense protective surface rust layers,which are produced through changing the alloy elements.Therefore,the weathering steel can be used without coatings,and there may be corrosion and fatigue coupling damage problems when the weathering steel is applied to highway and railway bridges.Based on a fully welded and non-coated weathering steel bridge of the Weilai railway,the fatigue damage analysis of key components and welded joints under train dynamic actions were carried out.The fatigue life assessment considering the influence of corrosion degradation was performed.The train-track-bridge coupling system model was established.The dynamic responses of key bridge truss components under high-speed train dynamic loads were obtained.The fatigue damage degree under the train passing vibration effect was analyzed.To further evaluate the fatigue damage conditions of welded joints,the multi-scale coupled finite element model that contains a refined joint model was established.The fatigue damage degree of the welded bridge joint under different train speeds and track irregularities were analyzed.The influence of environmental corrosion was then involved into the fatigue damage evaluation.The fatigue service life of critical bridge members and joints under corrosive environments and the train running vibration conditions were discussed and compared.Results are drawn as follows.The fatigue damages of different railway bridge truss members are different.The bridge members with the lower rigidity and shorter load paths have greater fatigue damage degrees.The fatigue damage degree located decreasingly at joint cross beam,web chord,bottom truss chord,and upper truss chord.The track irregularity and train running speed have significant influence on the dynamic stress responses at the welded joint.The 120 km/h train running case has the maximum resonance responses.The environmental corrosion can reduce the fatigue life of railway bridges,and the fatigue damage degrees are different at different bridge components.The research results can provide references for the fatigue life assessment and design of the same type of railway steel truss bridge in corrosive environments.
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