Analysis The Characteristics Of Lateral Seismic Response Of Cable-stayed Bridge And The Reasonable Aseismic System

With the rapid development of China’s economy,China’s infrastructure has made great progress.As a force majeure force,earthquakes have a great destructive effect on bridge structures,especially large-span cable-stayed bridges.For the research on the seismic performance of long-span cable-stayed bridges,domestic and foreign researchers have done a lot of work.The longitudinal seismic problem is the focus of research,but engineering practice shows that the horizontal seismic problem is also very prominent.This paper focuses on the characteristics of lateral seismic response of cable-stayed bridges and the rational constrained seismic system.The main research work and conclusions of this paper are as follows:First of all,for the initial lateral fixed restraint system of a long-span double-tower cable-stayed bridge(ie,the main girders are laterally fixed at the main tower,auxiliary piers,and transition piers),a finite element analysis model was established using SAP2000,based on nonlinearity.The time-history analysis method was used to study the lateral seismic response characteristics of the bridge,including the seismic internal force response characteristics of main towers and bridge piers,the seismic displacement response characteristics of main towers and main beams,and the seismic shear and deformation response characteristics of spherical steel bearings;The C/D ratio has comprehensively evaluated the lateral seismic performance of the bridge.Studies have shown that the two-sided transition piers,auxiliary piers,and bearings are the weakest link of the bridge and are most likely to be destroyed in the earthquake.Then,three different lateral restraint systems were compared for the weak seismic link of the bridge,namely the lateral fixed restraint system,the lateral sliding restraint system,and the restraint system that allowed the support to break.The lateral seismic response of cable-stayed bridges under three different restraint systems is discussed,and the parameter sensitivity analysis of the friction coefficient after the failure of the bearings is performed.The study shows that the lateral fixed restraint system increases the overall lateral stiffness of the cable-stayed bridge,resulting in an increase of seismic inertial force,which increases the overall seismic internal force response of the bridge;the lateral sliding system can significantly reduce the seismic internal force response of transition piers and auxiliary piers,but The displacement response of the main tower and the main girder is quite large and cannot meet the requirements of lateral stiffness;in the case of allowing the bearing to be destroyed,the friction energy of the ball bearing can improve the seismic response of the transition pier and the auxiliary pier,and it can also reduce the main The lateral displacement of the beam and the tower top,but put forward higher requirements for the maintenance and reinforcement after the earthquake.Finally,based on the comparison of the above three constraint systems,a viscous damper is proposed for the lateral restraint system of the cable-stayed bridge,and the arrangement conditions of the two dampers are set,ie only the auxiliary pier is provided with a damper and a transition pier + auxiliary Piers are equipped with dampers.Using nonlinear time-history analysis method,the damper parameters were optimized for both layouts.The optimization parameters were damping coefficient C and velocity index α.The two parameters were optimized for crossover.The analysis shows that the optimal parameter combination is α=0.3 and C=3000 when the auxiliary pier is equipped with a damper,and the optimal parameter combination is α=0.5 and C=5000 in the case that the auxiliary pier and the transition pier both have a damper..The constraint system under the combination of these two optimal parameters is compared with the above three constraint systems,and finally the reasonable lateral restraint system of the cable-stayed bridge is the restraint system with the damper installed in the auxiliary pier.Under this system,the seismic internal forces of the various piers and towers of the bridge are significantly reduced,the displacement of the tower top and the main beam is significantly reduced,and the bearings also meet the seismic performance requirements.The research results of this paper can provide reference for the lateral seismic design and evaluation of the same type of cable-stayed bridges.