Load Test and Fatigue Life Evaluation for Welded Details in Taizhou Yangtze River Bridge

To study the fatigue performance of welded details in the orthotropic steel decks, the steel box girder for Taizhou Yangtze River Bridge is taken as the research object. Based on the field monitoring data obtained from the load test, the stress response test of the orthotropic steel box girder under wheel loads is performed and the correctness of the vehicle test data obtained from the field monitoring data also have been verified by the numerical results of the finite element model. Based on the Miner linear cumulative damage theory, the S-N curve of the Eurocode3 specification is referenced, and the fatigue life calculation formula of the welded details is determined according to the actual structural features. The fatigue life evaluation of the four typical welded details is obtained. The results indicate that: The load test data is compared and verified by the numerical result of finite element model. The local effect of stress distribution is remarkable. The stress measurement points on the four typical welded details are mainly based on low amplitude stress cycles. Most of the stress ranges are 2-10 MPa, among which the stress range of the welded details at the U-rib butt joint is larger. The fatigue life of welded details in the 14 mm thick top plate is smaller than that of the 16 mm thick top plate corresponding to the fatigue life of the welded details. The rib-to-rib butt welded joints and the openings of the diaphragms were prone to fatigue failure. Among them, the welding details of the 14 mm thick U-rib butt joints first appeared fatigue failure. The arrangement of the diaphragm can effectively increase the fatigue life of the top-U rib weld and improve the fatigue performance at this detail.