Residual Life Assessment Of An Existing Riveted Steel Truss Bridge Considering Time-dependent Deterioration Of Corrosion

Existing riveted steel truss bridges are widely used on highways and railways in the world,and most of them have been in service for more than half a century.The fatigue resistance will be significantly degraded under the combined effect of environmental corrosion degradation and repeated traffic loads during the service period.With the prolongation of service life,the structural safety issues during service are becoming more and more serious as a result of the contradiction between the significant degradation of corrosion-induced fatigue resistance and the increase in fatigue performance requirements.In this paper,the following research work is carried out based on a typical existing riveted steel truss bridge.(1)The history and developments of fatigue life assessment,corrosion analysis,and corrosion fatigue research worldwide of existing riveted steel truss bridges have been introduced,then the disadvantages of present studies have been expounded.Finally,the research objectives and contents of this paper have been proposed.(2)The multi-scale finite element models of an existing riveted steel truss bridge have been built.Based on rain-flow counting method and linear fatigue damage accumulation criteria,the most dangerous structural fatigue member and joint plate have been identified.And the dominant fatigue failure path of the structure without the effect of corrosion degradation have been obtained.(3)The corrosion investigation on the typical existing riveted steel truss bridge has been carried out.Based on statistics measured from the investigation,time-dependent corrosion equations of components have been deduced.Then,the machine learning method has been applied to analyze the deterioration effect of corrosion on fatigue resistance,and the fatigue resistance evaluation S-N curves of the existing riveted steel truss bridge in service considering the corrosion degradation effect have been obtained.(4)Based on the random traffic data and the historical changes of the traffic flow,a random traffic fatigue load model has been established.Taking into account the timedependent deterioration of fatigue resistance as a result of corrosion,the residual fatigue life of the bridge has been assessed,and the migration of dominant fatigue failure path of the structure has been analyzed.The research results can provide a scientific basis for the service safety and maintenance decisions of the existing riveted steel truss bridge structures.