Numerical Analysis Of Seismic Performance Of Precast Segmental Bridge Piers And Bridge Structures

Precast segmental bridge piers have gradually become a research hot topic in bridge seismic research due to their small epicenter damage and good post-earthquake recovery ability.However,the energy dissipation capacity of precast segmental bridge piers is weak,and the capacity to withstand lateral loads and shear forces is insufficient,which limits the application of this type of piers in high intensity seismic zones.In order to improve the performance of precast segmental bridge piers in high intensity areas,suggestions and references were provided for seismic isolation of precast segmental bridge piers.In this paper,the finite element model of single column pier and bridge structure of precast segmental bridge piers was established by numerical simulation method,and the seismic performance of single column pier and bridge structure of precast segmental bridge piers was studied.Energy dissipation devices were added to the piers and isolation technology was applied to improve the seismic performance of the piers and bridge structures.The specific research work of this paper includes the following aspects:(1)This paper summarized the practical engineering application and experimental research of precast segmental bridge piers at home and abroad,summarized the research hot topics and shortcomings of precast segmental bridge piers at the emergence stage,and put forward the main contents of this paper.(2)The test pier speciment in the literature was selected as the prototype pier,three most commonly used numerical models of precast segmental bridge piers were established: fiber model,solid model and centralized plastic hinge model,and the quasi-static loading simulation comparison was carried out.The results show that the fiber model has a good performance in the simulation of pier hysteresis performance,lateral bearing capacity,energy dissipation capacity,calculation time and accuracy.The simulation method of pier fiber model based on Open SEES will be adopted in the following chapters.(3)A dry joint element was composed with rigid element,non-linear beam-column element,zero-length element and ENT material.The numerical simulation results of the fiber model based on the dry joint element was compared with the quasi-static test results of 1:3.5 scale piers in the literature,it was proved that the dry joint element can be used to simulate the dry joint area of precast piers.Energy-dissipating steel bars,enclosed steel tubes and rubber bearing cushions at the bottom of piers were set up as additional energy-dissipating devices on this pier model and the quasi-static cyclic loading simulation of model was carried out.The hysteretic capacity,internal force of prestressing tendons,cumulative energy dissipation,residual displacement and equivalent stiffness of different energy-dissipating devices for precast segmental bridge piers were studied.(4)On the basis of the previous chapter,the seismic response of precast segmental bridge piers with energy-dissipating steel bars was further studied.Based on Open SEES,four groups of precast segmental bridge piers models with different energy-dissipating steel bar ratios were established.Nonlinear dynamic time history analysis and incremental dynamic time history(IDA)analysis were carried out for pier models.The results show that the influence of near-fault ground motion on precast segmental bridge piers was greater than that of ordinary ground motion when the seismic intensity was large;the stiffness of piers was increased by adding energy-dissipating steel bars,which can reduce the seismic response of piers under seismic action.However,the increase of the reinforcement ratio of energy-dissipating steel bars will reduce the plastic deformation capacity of piers,restrain the opening of pier joints,and increase the residual displacement under the same lateral displacement amplitude.(5)Based on Open SEES,the analysis model of precast segmental bridge pier continuous girder bridge with no isolation and pier top isolation was established,and the non-linear dynamic time history analysis of continuous beam bridge model was carried out to explore the seismic response and isolation effect of bridge structure with or without isolation system under earthquake excitation.The results show that precast segmental bridge pier continuous girder bridge with seismic isolation had longer natural vibration period,smaller epicenter displacement,pier bottom shear force,pier bottom bending moment and residual displacement after earthquake,and the advantages of seismic isolation were more obvious in large earthquakes.