Multi-point Impact Earthquake Simulation Shaking Table Test Of Bridge Structure And Research On Sensitivity Of Impact Response Parameter

Under strong earthquake conditions,due to the differences in the dynamic characteristics of adjacent spans of bridge structures or the influence of non-uniform seismic actions,poundings can easily occur,leading to damage.Bridge collision damage not only causes road traffic paralysis,but also results in huge economic losses and casualties,and greatly hinders earthquake relief work.Therefore,it is necessary to study the multi-point collision response of bridges under seismic conditions in order to ensure the safety and reliability of bridge engineering as much as possible.Based on this,this paper simplifies common bridge structures according to mechanical models and conducts multi-point collision vibration table tests,and analyzes the sensitive parameters affecting collision response using finite element software.The main research work includes the following aspects:(1)Based on literature review and on-site investigations,this paper summarizes the seismic damage caused by collisions in bridge structures under earthquake conditions,discusses the basic theories and research methods of collision response analysis for bridge structures,analyzes the mechanism of bridge structure collisions,and reveals the types of sensitive parameters affecting collision response and the basic principles for selecting collision elements.This lays a foundation for the subsequent research.(2)In view of the large spatial distribution of bridges and the difficulty in conducting large-scale reduced-scale model vibration table tests,this paper identifies key research parameters,designs and produces two sets of simplified collision models for earthquake simulation vibration table tests.The first set of models simulates the collision between the main beam and the two side piers,and the second set of models simulates the collision of the main beam with three piers of different stiffness.Through experiments,the effects of bridge piers on the displacement response of the main beam,collision response at gaps,and internal force response at pier bottoms under multi-point collision effects were discussed,as well as the effect of pier stiffness on the displacement response of the main beam and internal force response at pier bottoms.(3)Based on the models used in earthquake simulation vibration table tests,a finite element model was established using the large-scale general finite element software Ansys,and some experimental conditions were calculated.The simulation results were in good agreement with the experimental results,indicating that the selection of finite element model parameters was correct and reasonable.On this basis,the effects of changes in collision-sensitive parameters such as collision stiffness,collision damping,initial gap,and lower structure height on the multi-point collision response of simplified collision models for bridge structures were discussed.(4)A three-span continuous beam bridge was selected,and a spatial analysis model of the bridge was established on the Ansys platform to conduct multi-point collision response analysis under seismic excitation.The results show that collision can reduce the displacement response of the main beam to a certain extent.By changing the collision sensitive parameters,similar calculation results to those of the simplified collision model of the bridge were obtained,indicating that it is feasible to study the multi-point collision behavior of bridge structures based on simplified collision models.