| Anchoring structure is a critical position affecting the structure safety of steel bridges.Featuring complex stress concentration and weld intensity,its fatigue performance is difficult to be grasped by bridge designers.Based on the background above,it is necessary to undertake a systematic study on the fatigue performance of pin hinge anchoring structure.In this thesis,Guangzhou Guidan rigid frame road-cross(24+160+24)m arch bridge is taken for example.The load transfer mechanism and fatigue performance were systematically studied through finite-element analysis and model test.The main conclusions are as follows:1.The finite element model was established to study the stress distribution on the anchorage zone and the main welds under the design load.The results indicate that there is a certain stress concentration in the anchorage zone;the transmission of cable force in the anchorage zone is smooth,with an uneven distribution in the welds.Three main welding lines between ear plate and the box girder transfer 80%of the total cable force.2.According to the actual train operation plan,the fatigue load was determined by the Miner linear cumulative damage criterion.A 1:2 scale test model is designed to study the fatigue performance of the pin hinge anchoring structure.No fatigue crack was found after 2.6 million times' cyclic loading.The stress test results of each measuring point show a small fluctuation and a linear change in the loading and unloading curves,and the fatigue stress was checked according to the standard.The test results show that the pin hinge anchoring structure has good fatigue resistance and enough safe reserves.3.Extended finite element method(XFEM)was used to simulate the weld toe crack propagation process,and the stress intensity factors during each stage of cracking process was calculated.A preliminary prediction for fatigue life of the pin hinge anchorage structure was made to provide a design and construction basis for future use in similar structures... |
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