竖向地震动加速度反应谱特性

以33次地震中的地表地震动记录为数据基础,考虑场地条件、震级和距离的影响,分别对竖向地震动的加速度规准化反应谱和双规准化反应谱进行了研究。结果表明,规准反应谱明显受到场地条件、震级和震中距的影响,不同场地、距离和震级的平均规准反应谱之间差别显著;相比较而言,不依赖于场地、距离和震级的平均双规准反应谱之间却表现出良好的规律性和一致性。双规准反应谱的统一特性可以为竖向地震动设计谱的预测提供参考依据。     

The relation between the response spectrum and the phase diference spectrum

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近断层竖向与水平向加速度反应谱比值特征

显著的竖向地震动是近断层地震动区别于远场地震动的重要特征之一,为更合理地确定竖向地震动作用,研究了近断层区域竖向地震动的反应谱特征及其与水平向反应谱比值的影响因素.首先,选取1952—1999年世界范围内震级在M5.4—7.6之间的18次地震的地震动记录,研究竖向地震加速度反应谱及其与水平向加速度反应谱比值特征;然后统计分析了断层距、场地条件、震级以及断层机制对竖向与水平向加速度反应谱比的影响.结果表明,一般情况下竖向加速度具有更丰富的短周期分量,并且竖向加速度反应谱衰减较慢;断层距在20km以内的近断层区域、软弱土层场地、中等震级地震和逆断层大震级中长周期范围等条件下,具有较大的竖向与水平向加速度反应谱比值;在近断层区域的结构抗震设计中应充分考虑竖向地震动的影响.     

Artificial ground motion compatible with specified ground shaking peaks and target response spectrum

1 Introduction Time history analysis is usually needed not only for the seismic design of important structures, such as nuclear plants, large concrete dams and super high-rise buildings, but also for seismic performance based design. Performance-based design requires tha knowledge of the entire process of nonlinear seismic responses of structures be obtained, which depends on the ground motion time history as input for this analysis. However, because the observed strong-motion recordings are l…     

从反应谱求功率谱的精确方法及其应用

本文对由反应谱求功率谱的近似公式的误差进行了讨论,从而说明了精确求解地震动功率谱的必要性,并从构造函数的特征出发,提出了一类符合要求的构造函数族,同时对其参数的取值加以讨论。最后给出了一个算例,展示了从反应谱求功率谱的精确方法与近似方法在数值上的差别,以及对人造地震动的影响。     

非平稳人造地震动反应谱拟合的震记录应用研究

利用天然地震记录数据提取其非平稳相位数据的方法、论证人造地震动方法的可行性和合理性,并以呼和浩特市基岩场地非平稳人造地震动预测拟合应用为例,进行人造地震动反应谱拟合.本研究方法明显加强地震监测数字化记录与结构地震动输入预测模拟的密切联系,使地震动预测因充分利用近场地震观测资料而得到质的飞跃.     

北京盆地结构对长周期地震动反应谱的影响

建立了北京盆地含起伏地形的地下介质三维速度结构模型, 以有限差分方法对盆地内的3次地震动进行了数值模拟． 计算了地表加速度反应谱, 论证了反应谱的有效周期范围, 从而获得了盆地结构对长周期段反应谱的平均放大系数, 并对不同周期时反应谱的平均放大系数进行了分区, 为今后城市的合理规划和长周期建筑物的建设提供了抗震设防参考． 最后对反应谱平均放大系数与等效沉积物厚度之间的关系进行了回归, 得出了反应谱放大系数随沉积物厚度增大而增强, 以及随周期增大而减弱等结论．      

Modeling of spatially correlated,site-reflected,and nonstationary ground motions compatible with response spectrum

Seismic risk analysis and mitigation of spatially extended structures require the synthesis of spatially varying ground motions in the response history analysis of these structures. These synthetic motions are usually desired to be spatially correlated, site reflected, nonstationary, and compatible with target design response spectra. In this paper, a method is presented for simulating spatially varying ground motions considering the nonstationarity, local site effects, and compatibility of response spectra. The scheme for generating spatially varying and response spectra compatible ground motions is first established for spatial locations on the ground surface with varying site conditions. The design response spectrum is introduced as the “power” spectrum at the base rock. The site amplification approach is then derived based on the deterministic wave propagation theory, by assuming that the base rock motions consist of out-of-plane SH wave or in-plane combined P and SV waves propagating into the site with assumed incident angles, from which tri-directional spatial ground motions can be generated. The phase difference spectrum is employed to model ground motions exhibiting nonstationarity in both frequency and time domains with different site conditions. The proposed scheme is demonstrated with numerical examples.     

基于Simulink的桩-土-结构相互作用反应谱分析

在Simulink环境下对桩-土-结构相互作用系统进行了仿真计算分析,并利用反应谱理论研究了SSI效应对上部结构动力响应的影响.采用集中参数模型考虑桩-土对上部结构的影响,上部结构简化为单质点模型,给出了桩-土-结构系统的状态方程,根据模型状态方程在Simulink环境下建立系统的仿真模型,得到了不同场地条件下SSI效应对上部结构加速度谱与位移谱的影响规律.计算结果表明:位移谱基本保持着“刚性假定＜Ⅰ类场地＜Ⅱ类场地＜Ⅲ、Ⅳ类场地”的规律;加速度谱受场地影响的规律不太明显,但在场地较软、桩基刚度较大时,加速度比刚性假定下的要小,而在其他情况下,加速度则比刚性假定下的要大.     

基于强震记录的核电厂抗震标准反应谱研究

依据基岩场地上的汶川地震强震记录,分析了地震动地面峰值和核电站抗震标准反应谱的特性,证明了在推导和使用标准反应谱时所考虑的地面峰值加速度与地面峰值速度之比(PGA/PGV)受地面峰值加速度和震中距的影响,将对标准反应谱形状产生明显的影响.另外还发现了基岩场地的竖向峰值加速度可能要远比通常认为水平向峰值加速度的2/3大....     

基于相位余弦分区的人造地震动反应谱拟合

为解决人造地震动拟合时出现的经幅值调整仍未收敛的问题,分析了造成相位调整效果不稳定的原因并给出有关参数的补充公式,提出由地震动各分量反应对应的相位余弦符号来实现相位分区并给出各分区的相位调整方法.针对经相位调整仍无法收敛情况,在相位调整完成后继续使用幅值调整来改善拟合效果.算例表明本方法可有效实现迭代收敛并生成较好拟合...     

地震动强度对场地地震反应的影响

通过对场地地震反应的研究发现,地震动强度不同,同样的场地对地震动的影响也不同,得到的反应谱形状也不同。目前我国抗震设计规范中不同烈度下的设计反应谱形状完全一致,没有考虑地震动强弱对相同场地反应谱形状的影响。     

抗震设计反应谱的标定方法

抗震设计反应谱是结构抗震设计的主要依据,设计反应谱的标定是确定地震动输入的重要环节。文中详细地总结了设计反应谱标定的基本原理和几种常用的设计反应谱标定方法,介绍了我国建筑抗震设计反应谱参数的确定方法和统一抗震设计反应谱的研究现状及应用前景;对不同设计反应谱标定方法中存在的问题进行了评述;提出抗震设计反应谱标定方法中有待进一步研究的问题。     

基于目标反应谱和包线的地震动合成

本文给出了以目标反应谱和目标包线函数为双目标函数的人工地震动合成方法,不仅使人工地震动符合目标反应谱,还在迭代过程中对地震动波形进行调整,使之基本符合目标包线函数,并消除了加速度时程的基线偏移,使速度时程和位移时程更为合理。本文认为当研究非线性结构体系的动力反应规律时,有必要对输入的人工地震动时程的反应谱和包线均进行比较准确的控制,使人工地震动时程符合多个统计特征。     

抗震设计谱的发展及相关问题综述

抗震设计谱是地震荷载的表征和工程抗震设计的基础。首先对国内外抗震设计反应谱的发展、演变进行了阐述，指出现今反应谱理论以及在此基础上建立的抗震设计谱所取得的进展；总结了被广泛使用的各种抗震设计谱所存在的问题，指出了解决问题的可能途径，简要介绍了双规准反应谱的概念和统一设计谱的思想；探讨了抗震设计谱的发展趋势以及所涉及的新课题。     

Assessing adequacy of spectrum‐matched ground motions for response history analysis

Response spectrum matching is commonly used to generate ground motions with response spectra matching a scenario target spectrum. There is some debate in the literature about whether spectrum‐matched motions lead to biased structural analysis results. Furthermore, there are no objective, quantitative criteria available for deciding whether a ground motion has been manipulated excessively by spectrum matching, and whether large modification may also lead to bias. This study investigates both of these issues by presenting the results of structural analysis using two reinforced concrete moment frame models and two earthquake scenarios, with suites of unmatched and matched ground motions. Through comparison with a robust benchmark, it is shown that no significant bias is introduced by spectrum matching. The period range and target damping values for matching are also investigated, and matching up to three times the fundamental period is shown to be beneficial in reducing dispersion in the results. Finally, these analyses were also used to investigate whether large changes in the ground motion lead to biased analysis results. Several potential measures of change are investigated, including those based on peak absolute ground motion, cumulative squared ground motion (absolute or normalized), and input energy into single‐degree‐of‐freedom systems. Although no systematic, statistically significant correlation is found for the analysis results in terms of any of these measures of change, tentative criteria are proposed, which may be used by analysts to aid in the decision of whether to accept or reject a spectrum‐matched motion. Copyright © 2012 John Wiley & Sons, Ltd.     

Generating ground motion by two new techniques of adding harmonic wave in the time domain and approximating to response spectrum as a whole

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Artificial ground motion compatible with specified peak velocity and target spectrum

In this paper, a method, which synthesizes the artificial ground motion compatible with the specified peak velocity as well as the target acceleration response spectrum, was proposed. In this method, firstly, an initial acceleration time history α8^（0） （t）, which satisfies the prescribed peak ground acceleration, the target spectral acceleration ST（ω, ζ）,and the specified intensity envelope, is generated by the traditional method that generates the requency domain; secondly,α8^（0） （t）is further modulated by superimposing narrow-band time histories upon it in the time domain to make its peak velocity, approach the target peak ground velocity, and at the same time to improve its fitting precision to the target spectrum. Numerical examples show that this algorithm boasts high calculation precisions.     

基于模拟退火算法的设计反应谱标定方法

反应谱的标定是抗震设计的基础工作之一,模拟退火算法是基于模拟固体退火过程而提出的多参数优化组合方法。本文提出将模拟退火算法应用于设计反应谱的标定,并概述了模拟退火算法的基本原理及特点,介绍了运用MATLAB基于模拟退火算法对反应谱进行标定的过程。检验了将模拟退火算法应用于场地相关谱标定的可行性和合理性,给出了将其应用于工程场地地震安全性评价中设计反应谱标定实例。通过检验和实例分析可以看出,基于模拟退火算法的反应谱标定方法所给出的设计反应谱谱形真实地反映了原地震反应谱的特征,较客观的反映了场地相关反应谱的峰值和周期特征。