考虑竖向地震作用新型三维隔震结构时程分析

Dynamic analysis of the new three dimensional isolation structures considering vertical seismic action

竖向地震作用会引起额外的水平力并增大结构的P-Δ效应。本文将竖向地震作用引入到水平运动微分方程中,采用MATLAB求解非线性微分方程,研究了竖向地震作用对水平地震反应谱的影响,并在此基础上考虑竖向位移对新型三维隔震墩水平刚度的影响,进行了新型三维隔震结构非线性时程分析。研究结果表明:考虑竖向地震作用引起的P-Δ效应后,结构自振周期随时间变化,加速度反应谱值减小而位移反应谱值增大;结构高度越小、结构周期越长,竖向地震作用对反应谱的影响越大;考虑竖向地震作用及竖向位移对弹簧水平刚度的影响后,新型三维隔震结构加速度反应减小、位移反应增大,新型三维隔震结构减震系数可以控制在0.5以下。

Vertical seismic action could cause additional horizontal force and enhance the P-△effect.The vertical seismic action was introduced into horizontal governing equations.A MATLAB program was prepared to solve the nonlinear governing equations and the influence caused by vertical seismic action on horizontal spectra was analysed.Based on the program,the nonlinear time history analysis was carried out considering the horizontal stiffness changes of three dimensional isolation piers which was caused by the vertical displacement.The results show that the period of structure changes with time after taking the the P-△effect caused by vertical seismic action into consideration and the acceleration response decreases while the displace response increases.Smaller height of structures and longer structural period could cause greater influence.In addition,the acceleration of the new three dimensional isolation structure decreases and the decrease coefficient could be controlled under 0.5.