Finite Element Model Modification And Study On Seismic Ductility Evaluation Of Suspension Bridges

Earthquake often brings unbearable damage to human beings.With the development of economy,people pay more and more attention to the impact of earthquake on human activities.Considering the bridge plays a key role in the passage,domestic and foreign researchers have been constantly researching and exploring the seismic resistance of bridges.Among them,the study of long-span suspension bridges is still insufficient due to relatively few earthquake damage.At the same time,in recent years,the seismic design concept in the field of seismic engineering has begun to change from a single emphasis on seismic safety to a combination of safety and resilience.How to evaluate the seismic toughness of suspension bridges has attracted more and more attention.In view of this,on the basis of consulting a large number of relevant literatures on bridge seismic resistance,this paper explores the finite element model updating and seismic resilience evaluation analysis of long-span suspension bridges preliminarily.The specific works are as follows:(1)According to the structural system characteristics of the parallel cable-plane suspension bridge,a multistage model modification method for the substructure is proposed.Taking the Longmen Bridge in Karamay city as an example,the suspension bridge is divided into several relatively independent substructures.To take advantage of the relative independence of the transverse modes of the main tower,the reasonable elastic supporting parameters of the pile-soil interaction under the main tower are obtained by modifying the substructure model of the main tower.It is applied to the overall finite element model to complete the finite element model modification of the whole bridge,so as to improve the efficiency of the finite element model modification of this kind of suspension bridge.(2)Taking Yangmingtan Bridge in Harbin as an example,the seismic performance of parallel cable-plane self-anchored suspension bridge with double towers is studied by numerical simulation.Based on the sensitivity analysis of the main parameters which affect the vibration characteristics of the main tower,different types of central buckle are set in the middle of the span to compare the seismic response results of the key positions,and as a new seismic measure,the paper analyzed the influence of the central buckle on the seismic response of the suspension bridge.(3)The seismic vulnerability of self-anchored suspension bridges with parallelcable-plane of double towers is studied.The moment curvature curve of the bottom of the main tower is used to determine the damage indexes of different grades,and the capacity demand ratios of different damage indexes are calculated by IDA method to analyze the seismic vulnerability of the main tower.Then,the system vulnerability is obtained by combining the distribution with the bearing vulnerability.The seismic vulnerability of these two types of suspension bridges is compared with that of the other two kinds of typical suspension bridges.(4)The seismic resilience evaluation method of self-anchored suspension bridge with parallel cable-plane of double towers is explored.Based on the vulnerability analysis results,the loss function is determined and the resilience index is calculated by using the linear recovery model.The characteristics of this kind of suspension bridge and the improved method are compared and analyzed.