| In this article,by investigating bridge disease of steel box girder,Jia Shao bridge was taken as an example to study the monitoring of fatigue stress,stress concentration factor of welded details,the influence on fatigue life of residual stress,and the evalution methods of fatigue life.Main contents can be summarized as follows:1.Through fatigue stress monitoring of welded details in separate steel box girder and the methods of rain-flow counting,fatigue stress spectrum is eatablsihed.2.Based on analysis methods of hot-spot stress,hot-spot stress concentration factors of rib-to-deck welded details in steel orthotropic decks of separate steel box were computed with FEA methods.At the same time,the influence of geometrical parameters on hot-spot stress concentration was analyzed3.According to the welding technology of separate steel box,the welding temperature distribution and residual stress of welded details in steel orthotropic of separate steel boxwere simulated with numerical method.4.Based on the BS5400,the fatigue life of rib-to-deck welded detailsin steel orthotropic decks of separate steel box was evaluated with nominal stress method.The research results of hot-spot stress were summarized and hot-spot stressS-N curve method was used to evaluate the fatigue life of rib-to-deck welded detailsin steel orthotropic decks of separate steel box.Based on the Goodman modle,the residual stress was regard as the mean stress to analyze the influence of residual stress on fatigue life before or after whacking.As a result,the distribution of residual stress around weld toe of rib-to-deck welded detailsin steel orthotropic decks of separate steel box.and its influence on fatigue life was evaluated.At last,the influence of super weight vehicle on fatigue life was analyzed. |
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