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1.
计算地震动长周期反应谱的转换模型和方法 总被引：1，自引：0，他引：1
为减小长周期反应谱的计算误差,本文提出一个计算长周期反应谱的转换模型和与之相应的精确计算方法。该模型以地震动的速度和位移为输入荷载,有利于对荷载信号中的长周期噪声进行有效的控制,能够有效提升长周期地震动反应谱的计算精度和可靠性。 相似文献
2.
针对既有方法在分析TMD结构基于双过滤白噪声激励下结构响应的解表达式复杂而导致计算效率低的问题,提出了一种简明封闭解法。首先,利用双过滤白噪声谱的滤波方程与TMD结构的地震动方程联立,可将TMD结构基于复杂的双过滤白噪声激励准确的表示为易于求解的运动方程;其次,基于复模态法获得TMD耗能结构位移、层间位移的系列响应的复特征值及复模态参与系数;然后基于随机振动理论获得了TMD结构随机地震动系列响应（相对于地面绝对位移和结构层间位移）的功率谱统一形式的二次正交解,进而获得了TMD结构系列随机响应的0-2阶谱矩和方差的简明封闭解。最后研究了基于首超破坏准、Markov过程假设及串联失效模式的TMD结构的体系动力可靠度。通过一算例分析,表明了本文方法的正确性和高效性。因此,本文方法可用于各类线性结构基于复杂的随机地震动响应的分析及其动力可靠度计算。 相似文献
3.
Response spectrum analysis for non-classically damped linear system with multiple-support excitations 总被引：1，自引：0，他引：1
A new response spectrum method, which is named complex multiple-support response spectrum (CMSRS) method in this article,
is developed for seismic analysis of non-classically damped linear system subjected to spatially varying multiple-supported
ground motion. The CMSRS method is based on fundamental principles of random vibration theory and properly accounts for the
effect of correlation between the support motions as well as between the modal displacement and velocity responses of structure,
and provides an reasonable and acceptable estimate of the peak response in term of peak seismic ground motions and response
spectra at the support points and the coherency function. Meanwhile, three new cross-correlation coefficients or cross covariance
especially for the non-classically damped linear structures with multiple-supports excitations are derived under the same
assumptions of the MSRS method of classically damped system. The CMSRS method is examined and compared to the results of time
history analyses in two numerical examples of non-classically damped structures in consideration of the coherences of spatially
variable ground motion. The results show that for non-classically damped structure, the cross terms representing the cross
covariance between the pseudo-static and dynamic component are also quite small just as same as classically damped system.
In addition, it is found that the usual way of neglecting all the off-diagonal elements in transformed damping matrix in modal
coordinates in order to make the concerned non-classically damped structure to become remaining proportional damping property
will bring some errors in the case of subjected to spatially excited inhomogeneous ground motion. 相似文献
4.
Praveen K. Malhotra 《地震工程与结构动力学》2001,30(2):279-286
The ground motions induced by an earthquake are expressed by the histories of acceleration, velocity and displacement. It is generally assumed that the acceleration, velocity and displacement histories contain identical information, i.e. the velocity history is obtained by integration of the acceleration history, and the displacement history is obtained by integration of the velocity history. However, this is not always true. In conventional processing of ground motion histories, additional corrections are applied to the velocity and displacement histories, which are not reflected in the acceleration history. As a result, the three ground motion histories contain slightly different information, or they are not fully compatible with one another. The structural response computed from the acceleration history, therefore, does not correspond to the processed velocity and displacement histories. The purpose of this paper is to underscore the engineering difficulties associated with incompatible histories and to provide a method of computing the response spectrum, which is compatible with the acceleration, velocity and displacement histories. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
5.
The spatial variability of seismic ground motion is an important aspect for the earthquake resistant design of extended facilities. A modified response spectrum model, which addresses the problem of multiply supported structures subjected to imperfectly correlated seismic excitations, has already been developed (see References 1 and 2). The present paper proposes a modal combination rule for the case of non-uniform seismic input, which would be used together with the modified response spectrum model in order to compute physical responses. This rule, which accounts for modal cross-correlations, is an extension to an existing rule for the case of uniform seismic motions. It modifies the existing modal cross-correlation coefficients through a correction factor which depends on structural properties and on the characteristics of the wave propagation phenomenon. Finally, some practical considerations on the theoretical development are addressed. They aim at suggesting reasonable simplifications which render the modal combination rule more appealing for engineering purposes. The proposed practical combination rule is validated through a numerical experiment which also characterizes the effect of non-uniform seismic input on modal cross-correlation. 相似文献
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A method for parametric system identification of classically damped linear system in frequency domain is adopted and extended for non‐classically damped linear systems subjected up to six components of earthquake ground motions. This method is able to work in multi‐input/multi‐output (MIMO) case. The response of a two‐degree‐of‐freedom model with non‐classical damping, excited by one‐component earthquake ground motion, is simulated and used to verify the proposed system identification method in the single‐input/multi‐output case. Also, the records of a 10 storey real building during the Northridge earthquake is used to verify the proposed system identification method in the MIMO case. In this case, at first, a single‐input/multi‐output assumption is considered for the system and modal parameters are identified, then other components of earthquake ground motions are added, respectively, and the modal parameters are identified again. This procedure is repeated until all four components of earthquake ground motions which are measured at the base level of the building are included in the identification process. The results of identification of real building show that consideration of non‐classical damping and inclusion of the multi‐components effect of earthquake ground motions can improve the least‐squares match between the finite Fourier transforms of recorded and calculated acceleration responses. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
8.
结构平稳随机地震反应时域分析:方法 总被引：3，自引：3，他引：3
给出了三种常用的随机地震地面运动过程模型,即理想白噪声模型、金井清模型、改进金井清模型的相关函数表达式.引入状态向量,在状态空间中建立地震地面运动激励下的结构振动方程,并求解出结构的复模态特性和复模态反应.利用复模态叠加法推导出线性时不变多自由度体系在这三种随机地震动激励下的平稳协方差反应的解析式,可在时域内直接计算结构随机反应的统计特征.该方法物理概念清晰,结论简便明确,可作为实际工程结构平稳随机地震反应的实用分析方法. 相似文献
9.
为满足国家测震台网海量强震动观测数据的处理时效性、格式标准化、产品丰富度等需求,开发了兼容多类强震动观测站点且具备数据快速汇集、处理及归档等功能的强震动数据处理系统。该系统提供地震波形人机交互数据预处理界面,对加速度记录进行预处理,进一步分析预处理后的加速度事件波形数据,计算得到地震动各项参数,包括峰值加速度(PGA)、峰值速度(PGV)、峰值位移(PGD)、仪器烈度、持时、傅氏谱、反应谱和三联谱等,可以导出地震元数据、地震记录波形,对各类数据进行归档存储。该系统具有平台统一性、功能集成性、数据完备性等特点,有效提升了日常数据处理和管理能力,能在地震应急、震害评估和科学研究中发挥实效。 相似文献
10.
A method for stochastic seismic response analysis of non-classically damped structures 总被引：2，自引：1，他引：1
A method to calculate the stationary random response of a non-classically damped structure is proposed that features clearly-defined physical meaning and simple expression. The method is developed in the frequency domain, The expression of the proposed method consists of three terms, i.e., modal velocity response, modal displacement response, and coupled (between modal velocity and modal displacement response), Numerical results from the parametric study and three example structures reveal that the modal velocity response term and the coupled term are important to structural response estimates only for a dynamic system with a tuned mass damper. In typical cases, the modal displacement term can provide response estimates with satisfactory accuracy by itself, so that the modal velocity term and coupled term may be ignored without loss of accuracy, This is used to simplify the response computation of non-classically damped structures. For the white noise excitation, three modal correlation coefficients in closed form are derived. To consider the modal velocity response term and the coupled term, a simplified approximation based on white noise excitation is developed for the case when the modal velocity response is important to the structural responses. Numerical results show that the approximate expression based on white noise excitation can provide structural responses with satisfactory accuracy~ 相似文献
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利用小波多分辨率分析将地震动加速度分解为多频段小波分量,并运用复模态方法推导其计算层间隔震体系在地震作用下的动力响应公式,讨论各频段地震信号及结构响应的能量分配。同时利用小波时频工具分析地震动能量在时频域内的分布对层间隔震结构响应的影响,进而为考察地震动非平稳性对层间隔震结构非线性分析的影响提供方法。利用小波分析的以上优势,对一典型层间隔震结构分别进行弹性和弹塑性分析,结果表明弹性体系在地震作用下的响应可由该地震波各小波分量的响应叠加而得,地震动能量在时间上的集中会对层间隔震结构响应产生不利影响。 相似文献
13.
本文采用子空间迭代法分析了单层膜型网壳结构的自振特性;推导了大跨空间结构几何非线性地震响应时程分析的计算过程,编制相应的计算程序,用振型分解反应谱法与时程法进行了结构地震响应特性分析。研究表明:膜型网壳结构的抗震性能比较好;用反应谱法分析时,水平地震作用下截断振型取15、竖向地震作用下取60可满足工程设计要求;用反应谱法计算结构竖向地震响应是安全可靠的,但进行水平地震响应分析时,最终还需用时程法进行验算。 相似文献
14.
通过对隔震结构进行非线性动力响应分析,分别研究地震动参数和支座参数对结构地震响应的影响。首先,建立铅芯橡胶支座基础隔震结构的非线性运动方程;然后,以人工合成脉冲型地震动作为输入,运用MATLAB进行编程并求解结构在脉冲型地震动作用下的地震响应;最后,分别研究速度脉冲周期、支座屈服力、屈服后与屈服前的刚度比对隔震支座最大位移和上部结构层间位移的影响。研究结果表明,脉冲周期对结构地震响应影响很大,在进行隔震设计时应使结构自振周期远离脉冲周期;支座刚度比对结构地震响应影响较大,在进行支座选型时应重点关注;支座屈服力对支座位移的影响显著,屈服力越大,支座位移越小。 相似文献
15.
为探讨“最不利地震动”概念在地下结构抗震设计中的适用性,以软土地铁区间隧道为对象建立相应的地层-结构动力分析模型。以直径变形率为分析指标,基于动力时程方法研究18条不同输入地震动作用下隧道结构动力响应的分布及差异性,得出基于隧道地震响应的输入地震动排序,并通过调幅手段对比分析了地面峰值加速度（PGA）和隧道埋深变化对隧道结构地震动响应排序的影响规律。最后,评价了不同输入地震动参数,包括峰值加速度、峰值速度、峰值位移、绝对累积速度（CAV）和阿里亚斯（Arias）强度（IA）与隧道地震响应之间的相关性。分析结果表明:① 随着PGA从0.5 m/s2增加到2 m/s2,地震动排序发生明显变化,并且不同输入地震动引起的隧道地震响应差异显著提高,最不利地震动引起的直径变形率与平均值的比值从1.1增加到1.9;② 隧道从浅埋到深埋的过程中,地震动排序结果基本保持不变;③ PGA为2 m/s2时,隧道地震响应与基岩面峰值速度（PBV）的相关性最好,相关系数达到0.94,其次是与基岩面峰值位移（PBD）和IA,相关系数分别为0.62和0.48,相关性最差的是基岩面峰值加速度（PBA）和CAV,相关系数仅为0.37和0.22。研究结论可为今后软土隧道的输入地震动选择提供科学依据。 相似文献
16.
本文推导了基于位移激励计算单自由度体系拟速度谱公式,通过构造的脉冲位移时程对公式精度进行了验证;之后利用小波变换去除强震记录噪声而保留地震动永久位移,再基于去趋势项方法和滤波方法去除永久位移后,计算拟速度谱。算例结果表明:短周期段内,不保留永久位移的位移激励拟速度谱值与保留永久位移的位移激励拟速度谱值相差很小;中长周期段内,不保留永久位移的位移激励拟速度谱值总体上小于保留永久位移的位移激励拟速度谱值,且不保留永久位移时,滤波方法引起的拟速度谱降幅大于去趋势项方法所引起的拟速度谱降幅。因此,基于位移激励计算中长周期结构的地震反应时,应保留地震动永久位移,或基于去趋势项方法去除永久位移。 相似文献
17.
An accelerometer array at Pacoima Dam with three locations along the base and abutments recorded ground motion from a magnitude 4.3 earthquake on 13 January 2001. These records present an opportunity to study spatial nonuniformity for the motion in a canyon. Topographic amplification is characterized by ratios of response spectral displacement between locations, and seismic wave travel times are studied using cross‐correlation functions to obtain delays. Results of the analysis of the 2001 earthquake records are used to generate ground motion for the 1994 Northridge earthquake to replace records that were not able to be fully digitized. The ground motion generated for the Northridge earthquake is used as input to a finite element model of Pacoima Dam. The response of the model is consistent with observations of Pacoima Dam after the Northridge earthquake. Comparison of the response due to nonuniform input with the response due to uniform input demonstrates the importance of accounting for spatial nonuniformity because of the significance that the pseudostatic component has for the response to nonuniform input. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
18.
时-频反应谱是地震动幅值、频谱和持时三要素构成的空间三维谱.基于此,本文提出归一化时-频反应谱定义与计算方法,计算三条典型地震波的归一化时-频反应谱,对比分析表明:不同地震记录的时-频反应谱的幅值在时间和周期两个轴上的分布差别很大,具有不同时-频反应谱的地震波可能对结构地震响应产生不同影响;对12层钢筋混凝土框架结构模型进行弹塑性时程分析,通过结构地震反应、结构损伤曲线与输入地震动的归一化时-频反应谱对比,发现结构最大反应并不一定是造成结构倒塌的直接原因,用结构弹性阶段反应最大值进行抗震设计存在一定局限性,从而证明归一化时-频反应谱可有效用来分析地震动特性和结构破坏机理. 相似文献
19.
选取了具有不同峰值加速度、频谱和持时的6组地震动加速度时程作为输入,基于有限元数值模拟方法建立了二维均质边坡有限元模型,模拟分析了不同地震动作用下边坡模型的加速度和位移响应,揭示了地震动峰值加速度、频谱和持时对土坡地震响应的影响作用及其规律.研究结果显示:地震动峰值加速度、频谱和持时对土坡地震响应均有显著的影响,其中,边坡坡脚处和坡肩处的变形位移随地震动峰值加速度、特征周期和持时的增大而增大,坡体临空面各点的峰值加速度放大系数呈现随输入地震动特征周期的增大而增大、随输入地震动峰值加速度的增大而减小的规律.研究结果可为地震作用下边坡稳定性设计及防治研究提供参考. 相似文献
20.
The vertical response of suspension bridges to multi-support seismic excitations is investigated. A frequency-domain random-vibration approach is utilized to take into account not only the differences in ground motion inputs, but also the correlation among the various input motions. The earthquake response of the Golden Gate Suspension Bridge, California, is analysed. The ground motion inputs were taken from an array of time histories recovered from the Imperial Valley, California, earthquake (ML = 6.6) of 15 October 1979. Mean square displacement, stress and cable tension responses are obtained. An estimation of the expected peak response is made by comparing existing methods to the results of a time-domain analysis; it was found that a peak factor of 3.5 times the r.m.s. response is a good estimate of the expected peak response for this multiple-input seismic problem. 相似文献