Abstract
The existing fatigue assessment approaches were mainly conducted on the component level. The interaction of local component damage and the global response cannot be well addressed. In this study, three-dimensional (3D) fatigue crack propagation analysis approach based on global-local numerical model was implemented, and examined to be accurate and effective through a series of systematic experimental data obtained by Fisher. Afterwards, the approach was introduced into a typical steel truss bridge for realizing more refined fatigue assessment from the global structural level. The fatigue performance of the longitudinal steel welded beam in the steel truss bridge was investigated based on global-local model and local model respectively. It was found that there is no difference in terms of the fatigue crack growth mechanism between the simulation between global-local model and local model due to that the stress level of the whole structure is relatively low. At last, the effect of heavy haul train operation on the fatigue performance of the steel truss bridge was analyzed. It was observed that the residual life of the longitudinal steel welded beam would have an obvious reduction when the axle load was increasing. The research work in this study presents a technical solution for the fatigue assessment of the global structure and can provide beneficial reference for relevant practical engineering projects.
Highlights
The fatigue strength of welded steel beam is the significant design criterion for many steel bridges
The second one is that the interaction of local component damage and the global response cannot be considered as almost all the investigations so far can only focus on the component level with unchanged boundary conditions
Three-dimensional (3D) fatigue crack propagation analysis approach based on globallocal numerical model will be examined carefully
Summary
The fatigue strength of welded steel beam is the significant design criterion for many steel bridges. Three-dimensional (3D) fatigue crack propagation analysis approach based on globallocal numerical model will be examined carefully. This approach will be employed to estimate the residual life of welded steel beams in a practical steel truss railway bridge on the basis of the global-local modelling. According to Eurocode 3, the design S-N curve specified for the fillet welds of steel welded beam is FAT112, which means the fatigue strength in terms of 2× 106 cycles’ life is 112 MPa. the fatigue damage under a typical train passage can be obtained based on Palmgren-Miner linear damage rule. A refined local model of the longitudinal beam (Fig. 8b) with fixed end boundary conditions was established for contrastive study, to investigate the effect of global-local interaction on the fatigue life of structural details
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