Damping Performance Of Shock Absorber And Its Application Research On Railway Bridge

In recent years, with the rapid development of high-speed railway construction in our country, more and more attention has been paid to the seismic performance of high-speed railway bridge. To tackle the difficulty of ductility seismic design, vibration reducing isolation technology is no doubt an effective solution. However, due to the high demand on rigidity of railway bridges, the existing isolation devices applied to railway bridges, especially in high-speed railway bridges, are subject to a lot of restrictions. Based on the design philosophy of "bearing function separation", and by combining test with theoretical researches, this article systematically studied the feasibility of applying shock absorber-movable support system to high-speed railway simply supported girder bridge, as well as relevant seismic performances. The main research and conclusions are as follows:1. The requirements of shock absorber are considered, and the specific shock absorber structure, design method and mode of connection are systematically studied. (1) According to the shock absorber structure, the section change formula which is determined by three independent shape parameters is given, and the theoretical formula of main mechanical property parameters are deduced. (2) The simplified calculation of shock absorber elastic-plastic deformation under ideal elastic-plastic material conditions is given, and the shape parameters on the influence of the initial elastic stiffness and ductility are studied. (3) The connection between shock absorber and the pier, beam, the rigidity requirements of shock absorber-movable bearing system installed in high-speed railway simply supported girder bridges are analyzed.2. The pseudo-static experiment of two groups of full-size shock absorber specimens is carried out, the shock absorber energy consumption indicators such as hysteresis curves and viscous damping coefficient are emphatically studied, and the mechanical properties such as strength and stiffness are evaluated; Two methods are used to determine the restoring force model of shock absorber, and the load displacement and cyclic number on the influence of nonlinear stiffness are analyzed. FEM simulation analysis of shock absorber is conducted, the experiment results and the theoretical values are compared, and the theoretical formula correctness of mechanical performance parameters and rationality of the finite element model is verified.3. For passenger lines of 5 x 32 m simply supported girder bridge, the dynamic response of shock absorber-movable support simply supported girder bridges under the action of earthquake is studied; the damping effect of the shock absorber in the transverse and longitudinal directions is evaluated; for the contradiction between shock absorber-movable support bridges nonlinear problems and norm elastic response spectrum method, the equivalent linearization method is systematically studied, and the simple calculating process of shock absorber-movable support bridges is given.4. Based on the mechanical characteristics of bearing, the dynamic characteristics of bridge, and non-ideal factors in practice, various factors on shock absorber-movable support bridge seismic response and energy dissipation effect are systematically studied. (1) Single pier model is established to study the influence of shock absorber yield strength and bending stiffness ratio on the pier stress and beam displacement. (2) The influence of pier height on the shock absorber damping effect is studied, which leads to the conclusion that it should be used in low piers with natural vibration period less than 0.2. (3) The shock absorber-movable support restoring force model considering support friction is set up, based on which the influence of size of movable support friction and friction coefficient on the shock absorber-movable support simple support bridges response of earthquake and effect of energy dissipation is studied. (4) The line-bridge integration calculation model that considers orbit constraint is established, and a detailed analysis is conducted on the constraint of shock absorber energy dissipation effect.5. According to the characteristics of the CRTS II slab ballastless CWR structure, shock absorber-movable support beam ballastless CWR line-plate-bridge-pier space integration analysis model is set up, and the influence of bridge stretching, flexing and train braking on the CRTS II slab ballastless longitudinal force is studied. A design guide for the shock absorber-movable support beam bridge laying CRTS II slab ballastless CWR is provided.