基于场地特性多维多点地震动模拟及桥梁结构地震响应分析

发布时间：2018-03-27 23:28

本文选题：时-频特征参数　切入点：拟合功率谱　出处：《西南交通大学》2017年硕士论文

【摘要】：地震动输入正确与否是决定结构地震响应准确性的关键因素,特别是对于平面尺寸很大的大跨度结构物,比如桥梁、石油管线、海洋平台等生命线工程,若采用一致地震激励输入来做抗震分析,显然是不够准确的,因为大跨结构尺寸相对于地震波波长而言不可忽略,故各支点的地震动是不同的,且地震波数量有限性、随机性和不确定性等限制了多点直接动力分析法应用到实际工程。只有考虑了各支点的不同地震激励,才能确保大跨度结构地震响应的准确性,因此模拟生成具有特性参数的多点地震动是本文研究的重要方向。本文为了较为真实地模拟实际地震动的多维性、空间性及非平稳性,具体从以下几个方面进行研究:(1)针对地震动加速度时程的特征参数的话题进行了讨论,归纳和总结了地震动时域特征参数和频域特征参数的统计模型和相应的回归参数。(2)研究了拟合功率谱和拟合设计反应谱合成空间多点非平稳地震动时程,首先将设计反应谱转化为当量功率谱(目标功率谱);然后将功率谱密度函数矩阵由一维扩展到三维考虑地震波的多维性;再添加包络函数模型即考虑地震动非平稳性,并利用逆傅里叶变换合成了非平稳地震动时程;最后将合成的地震动时程采用频域方法迭代修正时程幅值,得到了满足精度要求的地震动时程曲线。(3)基于相位差谱合成空间多维多点非平稳地震动时程,首先研究了相位谱与地震动时程非平稳性的相互关系,采用计算机随机生成[0,2π]均匀分布的相位谱不能使地震动时程具有非平稳性;然后引入了相位差谱的概念,并研究分析了相位差谱的频数分布情况;最后构造相位差谱模型合成了空间多维多点非平稳地震动时程。(4)对比研究了基于PEER地震动数据库选取和人工合成两类地震动作用下桥梁结构的响应,验证了人工地震动的准确性。最后将人工合成的多维多点非平稳地震动用于瓯江特大桥地震响应计算。
[Abstract]:Whether the input of ground motion is correct or not is the key factor to determine the accuracy of seismic response of structures, especially for large span structures with large plane size, such as bridges, oil pipelines, offshore platforms and other lifeline projects. It is obviously not accurate to use uniform seismic excitation input to do seismic analysis, because the size of large span structure can not be ignored relative to the wavelength of seismic wave, so the ground motion of each fulcrum is different, and the number of seismic waves is limited. Randomness and uncertainty limit the application of direct multi-point dynamic analysis to practical projects. The accuracy of seismic response of long-span structures can only be ensured by considering the different seismic excitation at each fulcrum. Therefore, it is an important research direction to simulate the multi-point ground motion with characteristic parameters. In order to simulate the multi-dimensional, spatial and non-stationary of the actual ground motion, The topic of characteristic parameters of acceleration time history of ground motion is discussed from the following aspects. The statistical models of time-domain and frequency-domain characteristic parameters of ground motion and the corresponding regression parameters are summarized. The time history of multi-point nonstationary ground motion in space by fitting power spectrum and fitting design response spectrum is studied. First, the design response spectrum is transformed into equivalent power spectrum (target power spectrum); then, the power spectrum density function matrix is extended from one dimension to three dimensions to consider the multi-dimension of seismic wave, and then the envelope function model is added to consider the nonstationarity of ground motion. The time history of non-stationary ground motion is synthesized by inverse Fourier transform, and the amplitude of the time history is modified iteratively by frequency domain method. In this paper, the time-history curve of ground motion satisfying the precision requirement is obtained. Based on the phase difference spectrum, the multi-dimensional multi-point non-stationary motion time history is synthesized. The relationship between the phase spectrum and the nonstationarity of the motion process is studied. The random generation of phase spectrum by computer can not make the time history of ground motion nonstationary, then the concept of phase difference spectrum is introduced, and the frequency distribution of phase difference spectrum is studied and analyzed. Finally, the phase difference spectrum model is constructed to synthesize the multi-dimensional multipoint non-stationary ground motion time history. The responses of bridge structures under the action of PEER seismic database selection and artificial synthesis are compared and studied. The accuracy of artificial ground motion is verified. Finally, the synthetic multi-dimensional non-stationary ground motion is used to calculate the seismic response of Oujiang super bridge.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU311.3

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