Dynamic Analysis Of Half-Through Arch Bridges’ Suspender Subjected To Train Load

The half-through concrete filled steel tubular arch bridge has the advantages of strong vertical stiffness and small weight with a sense of beauty. As the train passes, the dynamic response of the bridge is significant. Especially for long span bridges, some of the components are slenderer than the main structure, so the steady accumulation of the local vibration can lead to the local damage, local vibration caused by the high-speed trains should not be neglected. In this dissertation, on the background of the design proposal of a 202m main span concrete filled steel tubular arch bridge, the BDAP is introduced to establish the spatial finite dynamic analysis model of the bridge, with the train-track-bridge coupled vibration theory the local dynamic behavior of the suspender is simulated.Firstly, the development status and structural features of railway arch bridge at home and abroad has been briefly introduced in this dissertation. Then it tells the simulation method of local dynamic behavior of the suspender, with the engineering background the details in modeling have been described. After that, the dynamic internal force of the suspender under train loads has been simulated. From the research it is possible to observe that the internal force of the short suspender is much larger than the long ones, with the train velocity increases, the stress amplitude of the short suspender becomes lager, and however the longer ones change a little. As the bending stiffness exists in the flexible suspender, the bending stress distribution caused by train loads is non-uniform and stress amplitude increases significantly. From the internal force response, the structure resonance has more influence on the bending moment than axial force. Dynamic amplification factors (DAF) is defined to express the dynamic effect of moving load, usually DAF is derived from the measurement or simulation of global traffic action effects in the main span. From the analysis, it is obvious that the DAF of the suspender derived from the stress is much larger than the DAF derived from the main span displacement.In the dynamic analysis, the local dynamic behavior of the suspender is simulated. From the result, some reasonable advises are proposed for anti-fatigue design and reducing the damage of structures.