长周期随机地震作用下超大跨斜拉桥的行波效应分析

发布时间：2018-04-08 11:00

本文选题：长周期地震动　切入点：功率谱密度　出处：《湖南大学学报(自然科学版)》2014年04期

【摘要】：从各个国家和地区的地震记录库中寻找出一些具有良好记录质量和基本场地资料的强震记录,并从中挑选出较为典型的长周期地震波,对比分析了不同场地条件下长周期地震波和普通地震波的平均加速度反应谱及其规范形式的分段拟合曲线.选取软土场地拟合反应谱作为目标反应谱,用迭代方法求取与目标反应谱相对应的功率谱密度函数,分析了基于长周期地震动加速度功率谱密度的特点.在此基础上,以某超大跨斜拉桥结构为背景,利用ANSYS软件建立三维有限元分析模型,分别以文中拟合的长周期地震动功率谱密度和普通地震动功率谱密度作为输入,采用直接求取位移的改进虚拟激励法,对超大跨斜拉桥结构进行了不同视波速下的行波效应分析.结果表明:长周期地震动功率谱密度的卓越频率明显低于普通地震动功率谱密度的卓越频率.长周期地震动功率谱作用下的桥梁左桥塔顶、右桥塔顶和桥面板跨中节点的位移响应功率谱值均明显大于普通地震动功率谱作用下的结果,桥梁塔顶位移响应功率谱均呈双峰分布.在本文算例中,考虑行波效应使超大跨斜拉桥结构的位移响应和弯矩响应结果有所减小.
[Abstract]:Some strong earthquake records with good recording quality and basic site data are found from the seismograms of various countries and regions, and typical long-period seismic waves are selected from them.The average acceleration response spectra of long-period seismic waves and ordinary seismic waves under different site conditions are compared and analyzed, as well as the piecewise fitting curves of their normative forms.The fitting response spectrum of soft soil is selected as the target response spectrum and the power spectral density function corresponding to the target response spectrum is obtained by iterative method. The characteristics of power spectral density based on long-period ground motion acceleration are analyzed.On this basis, taking a super large span cable-stayed bridge as the background, a three-dimensional finite element analysis model is established by using ANSYS software. The power spectral density of long-period ground motion and the power spectral density of ordinary ground motion are respectively used as inputs in this paper.An improved virtual excitation method for calculating displacement is used to analyze the traveling wave effect of long-span cable-stayed bridge structure under different apparent wave velocities.The results show that the excellent frequency of power spectral density of long-period ground motion is obviously lower than that of ordinary ground motion.The displacement-response power spectrum of the bridge at the top of the left bridge, the top of the right bridge and the mid-span of the deck of the bridge under the action of the power spectrum of long-period ground motion is obviously higher than that under the action of the power spectrum of the ordinary ground motion.The power spectrum of the top displacement response of the bridge tower is distributed with two peaks.In this paper, considering the traveling wave effect, the displacement response and the moment response of the long-span cable-stayed bridge are reduced.
【作者单位】：同济大学土木工程防灾国家重点实验室;
【基金】：国家自然科学基金重大研究计划资助项目(91315301)
【分类号】：U448.27;U441.3

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