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1.
弹塑性地震反应谱的长周期特性研究 总被引：3，自引：1，他引：3
在基于性能抗震设计中弹塑性反应谱在计算结构地震位移反应方面越来越受到重视。利用统计分析方法研究了等强度的延性需求谱和等延性的强度折减系数谱的长周期(至5 s)区段的特性,关注的重点是等位移准则和场地条件影响。给出了若干具有工程价值的结论:一是周期介于1.5Tg(地震动特征周期)和2.5 s之间的结构可近似认为等位移准则成立且与场地条件关系不大,这样确定的强度折减系数当位移延性系数小于等于4时结果将是偏于安全的;二是结构周期大于2.5 s后以硬土场地等延性强度折减系数谱或等强度延性需求谱代替软土场地谱求解系统强度需求或延性需求,将会得到偏于安全的结果。 相似文献
2.
考虑场地类别与强震持时的滞回耗能谱的特征分析 总被引：3，自引：0，他引：3
基于力或位移的结构抗震设计方法大多无法反映地震动持时的影响,而能量设计方法则能较好地弥补其不足。按场地类别和强震持时,将302条Northridge地震记录分为15组,对地震记录的峰值进行规一化处理,采用钢筋混凝土退化三线型恢复力模型,对单自由度体系进行弹塑性时程分析,研究场地类别、强震持时、强度屈服水平以及结构周期等因素对滞回耗能的影响。结果表明:在给定地震记录的峰值和屈服强度水平下,结构的滞回耗能依赖于场地条件和强震持时等因素;滞回耗能随强震持时的增加而增大,随场地特征周期的增加而增大。通过非线性回归分析,建立了与峰值加速度、峰值速度、强震持时相对应的简化滞回耗能谱的计算公式。 相似文献
3.
一种直接基于位移的抗震设计方法 总被引：1，自引：0，他引：1
马宏旺 《地震工程与工程振动》2007,27(2):45-50
与传统基于力的抗震设计方法相比,基于位移的抗震设计方法更适合实现基于性能抗震设计。本文在若干文献的基础上,提出了一种直接基于位移的抗震设计方法。该方法建立在结构屈服位移可由几何尺寸确定的基础上,根据不同水平地震作用下的目标设计位移,计算相应的延性系数,采用一定的Rμ-μ-Tn关系建立相应的非线性反应谱,以二折线模型模拟结构的性能曲线,然后根据结构不同的目标位移以及对应的非线性反应谱确定相应的有效周期,从中选择最小值作为设计结构的有效周期,根据有效周期计算结构的刚度,然后乘以屈服位移得到结构的屈服强度。根据结构屈服强度以及结构的超强系数,得到结构的设计基底剪力。该方法避免了设计中采用迭代计算,且一次设计就可以完成多水平设防的目的。 相似文献
4.
弹塑性时程分析一般用来评估和验算结构抗震性能,如何选取合适的输入地震动是其中关键工作之一。为给结构弹塑性时程分析选取地震动提供合理的参考参数,本文讨论了地震动反应谱参数与结构地震响应之间的相关性。首先建立了6层和7层两个钢筋混凝土(RC)框架结构数值模型,分别对两个结构进行了大量地震动作用下的时程反应分析,并考察了地震反应特点;然后将结构地震响应与地震动反应谱参数建立关系并进行了相关性分析。结果表明:对RC框架而言,结构地震响应与弹性谱参数相关性较小,与等强度反应谱相关性随标准屈服强度降低而增大,与等延性反应谱相关性随延性增大而增大,而与地震动输入能量谱在标准屈服强度较小时相关性最大。建议RC框架结构在进行地震反应时程分析时,可以参考地震动的弹塑性输入能量谱、等强度速度谱和等延性加速度或位移谱,以选取引起结构不同地震反应水平的输入地震动。本文结果和结论可供结构弹塑性时程分析选取合适的输入地震动参考。 相似文献
5.
双向地震动作用的拟等延性系数谱 总被引：1，自引：0，他引：1
首先建立了以强度折减系数表述的恢复力特性满足二维屈服面模型的理想弹塑性单质点系统(它在2个相互垂直的主轴方向上分别具有水平平动自由度)在双向地震动作用下的归一化运动方程。然后引入单向地震动作用下等延性系数的强度折减系数谱,给出了双向地震动作用的拟等延性系数谱(定义为系统分别承受双向和单向地震动作用,在同一主轴方向上的最大位移反应之比)最后通过硬土场地10组双向地震动记录拟等延性系数谱的统计平均结果,分析了结构周期、位移延性系数和阻尼等因素对谱值及结构双向地震反应的影响。结果表明,双向地震动作用与单向地震动作用相比主要增加结构较长周期方向的最大位移反应。若在基于位移的抗震设计中降低结构较短周期方向的设计位移延性系数,可在一定程度上降低双向地震动的不利影响。因定义的谱为比值形式,阻尼对其影响不大。 相似文献
6.
延性需求谱在基于性能的抗震设计中的应用 总被引：23，自引：4，他引：19
基于性能的抗震设计理论涉及如何简便而合理地确定结构在指定强度地震下的弹塑性位移需求。本文给出了利用延性需求谱求解结构位移需求的一般步骤:借助模态Pushover分析将多自由度体系分解为几个非线性单自由度体系,以考虑各阶振型的影响;利用延性需求谱计算对应模态的等效单自由度体系的延性及位移需求,并以一定方式组合转化为多自由度体系位移需求。最后,通过算例分析表明:利用延性需求谱求解结构位移需求是一种具有一定精度可为工程接受的简便方法,在基于性能的抗震设计中具有较好的应用前景。 相似文献
7.
剪切型结构的抗震强度折减系数研究 总被引：1，自引：0，他引：1
为了研究剪切型结构抗震强度需求的变化规律,本文基于单自由度体系的非线性时程分析,研究了不同场地条件下延性折减系数与位移延性系数和结构自振周期的关系;采用修正等效单自由度体系位移延性折减系数的方法,研究了剪切型多自由度体系的延性折减系数;以基于中国建筑抗震规范设计的代表不同抗震能力要求的RC框架结构为分析对象,通过静力弹塑性分析,研究了RC框架结构的体系超强能力。分析结果表明场地类别、位移延性水准和结构振动周期对单自由度体系的延性折减系数有显著的影响;多自由度体系的抗震延性折减系数明显比其相应的等效单自由度体系的抗震延性折减系数小;RC框架结构的超强系数一般随结构楼层数的增加而减小,随抗震设防烈度的增大而减小,内框架的超强系数比边框架的超强系数大。 相似文献
8.
强度折减系数既是基于强度的抗震设计中确定设计地震力的关键因素，又是基于性态的抗震设计理论中确定非弹性反应谱的主要依据. 本文结合我国抗震设计反应谱的形式和特点，应用823条国内外水平向地震动记录（充分利用了我国取得的强震记录），给出了一种考虑设计地震分组和场地类别的强度折减系数模型，研究了结构周期、延性、场地类别、设计地震分组、震级、震中距等因素对强度折减系数的影响. 结果表明:场地条件对强度折减系数的影响是不可忽略的，特别是对延性较大的短周期结构更应注意场地条件的影响；设计地震分组是影响强度折减系数的一个重要因素，在应用我国规范设计反应谱构造非弹性反应谱所用的强度折减系数必须考虑设计分组的影响；震级对强度折减系数的影响较小；如不考虑近场大脉冲地震动记录的影响，震中距对强度折减系数的影响是可以忽略的. 相似文献
9.
工程结构等延性地震抗力谱研究 总被引：28，自引：7，他引：21
研究结构的非弹性反应谱对改进现有的结构抗震设计、发展基于性态的抗震设计以及了解复杂地面运动特性与结构动力特性之间的关系具有重要的意义。利用大量的单自由度在强震记录作用下的弹塑性动力时程分析,对等延性地震抗力谱这一重要的非弹性反应谱进行了较为详尽的研究,给出了四类场地条件(基岩、硬土、一般土和软土)下的平均等延性地震抗力谱,总结了对工程结构的抗震设计和研究具有实际意义的规律和特征,并分析了场地条件、结构的延性系数以及周期等对等延性地震抗力谱的影响,提出了新的拟合公式,其成果可供抗震研究和设计直接应用。 相似文献
10.
能力谱方法在桥梁抗震性能评估中的应用研究 总被引：1，自引：0，他引：1
位移延性是桥梁抗震性能的重要指标之一,以Pushover分析为基础的能力谱方法能够考察结构在地震下的弹塑性位移响应,是抗震性能评估的一种有效手段.文中阐述了能力谱法的基本原理,说明了基于弹塑性反应谱的能力谱方法在求解性能点时不需要进行迭代计算;基于弹性设计反应谱建立了相对应的弹塑性反应谱,结合某实桥,将能力谱方法和增量动力分析方法进行了对比,并根据不同的地震基本烈度和场地土类型进行了抗震性能评估.分析认为,能力谱方法计算简便,对结构1阶振型的地震响应占主导时,具有较好的精度,并能够基于设计反应谱来考察结构的弹塑性抗震性能,可用于桥梁抗震性能的评估. 相似文献
11.
W. D. Iwan 《地震工程与结构动力学》1980,8(4):375-388
Inelastic displacement response spectra are determined for a broad class of single-degree-of-freedom hysteretic structures. Based on these spectra, effective linear period and damping parameters are defined as a function of ductility. A simple empirical formula is derived which may be used to estimate the mid-period range inelastic response spectrum of a general hysteretic structure given the linear response spectrum of the excitation. The estimates obtained from this formula are compared with those obtained by the Newmark-Hall method, the substitute–structure method and the ATC–3 tentative procedure. It is found that the empirical formula not only gives good estimates of the average behaviour of the inelastic spectrum, but also reproduces some of the details of the spectrum. 相似文献
12.
This paper presents a procedure for computing inelastic design spectra in terms of yield displacement. The procedure results in substantial computational savings as compared to the current procedures for computing the inelastic spectra in terms of displacement ductility. The proposed method is used to obtain inelastic design spectra for alluvium and rock. The results for alluvium are compared to those from the Newmark and Hall,10 Riddell and Newmark12 and Lai and Biggs4 studies. The findings indicate that for given ductility and frequency one may de-amplify the elastic response or reduce the elastic forces more for a structure on rock than for a structure on alluvium. A technique is presented so that the inelastic design spectrum can be scaled to any desired yield displacement and acceleration. An example is presented to illustrate how the proposed inelastic spectra can be used to compute the required ductility for a given system. 相似文献
13.
Deterministic and probabilistic floor response spectra 总被引：1，自引：0，他引：1
The paper presents a comparative study for computing floor response spectra (FRS) for complex structures. For the purpose of validation and evaluation of the methods for practical application, a systematic comparison of two concepts, classical deterministic and probabilistic, was carried out as an example of a nuclear power plants structure. The deterministic method utilizes time history analyses compatible with the prescribed design response spectrum. The probabilistic method uses an analysis of random vibrations for defining the probabilistic FRS influenced by random seismic soil movement. The seismic input is a power spectral density function (PSDF) compatible with the design response spectrum. The probabilistic approach based on PSDF provides satisfying FRS with far less effort and time consumption needed for calculation. 相似文献
14.
Djilali Berkane Hakima Harichane Zamila Çelebi Erkan Elachachi Sidi Mohammed 《地震工程与工程振动(英文版)》2019,18(3):497-509
The goal of this study is to provide a stochastic method to investigate the effects of the randomness of soil properties due to their natural spatial variability on the response spectra spatial variation at sites with varying conditions. For this purpose, Monte Carlo Simulations are used to include the variability of both incident ground motion and soil parameters in the response spectra by mean of an appropriate coherency loss function and a site-dependent transfer function, respectively. The approach is built on the assumption of vertical propagation of SH type waves in soil strata with uncertain parameters. The response spectra are obtained by numerical integration of the governing equation of a single-degree-of-freedom(SDOF) system under non-stationary site-dependent and spatially varying ground motion accelerations simulated with non-uniform spectral densities and coherency loss functions. Numerical examples showed that randomness of soil properties significantly affects the amplitudes of the response spectra, indicating that as the heterogeneity induced by the randomness of the parameters of the medium increases, the spectral ordinates attenuate. 相似文献
15.
场地类别划分与抗震设计反应谱的讨论 总被引：10，自引：1，他引：10
介绍了新的抗震设计规范(2001—07—20发布，2002—01—01实施)中场地类别划分和地震影响系数的有关内容，指出其中一些不相协调之处。最后，针对不同的问题建议相应的解决办法。 相似文献
16.
The paper starts with a discussion of the linear stochastic theory of ocean waves and its various nonlinear extensions. The directional spectrum, with its unique dispersion relation connecting frequency (ω) and wavenumber (k), is no longer valid for nonlinear waves, and examples of $\left( \mathbf{k},\omega\right) The paper starts with a discussion of the linear stochastic theory of ocean waves and its various nonlinear extensions. The
directional spectrum, with its unique dispersion relation connecting frequency (ω) and wavenumber (k), is no longer valid for nonlinear waves, and examples of ( k,w)\left( \mathbf{k},\omega\right) -spectra based on analytical expressions and computer simulations of nonlinear waves are presented. Simulations of the dynamic
nonlinear evolution of unidirectional free waves using the nonlinear Schr?dinger equation and its generalizations show that
components above the spectral peak have larger phase and group velocities than anticipated by linear theory. Moreover, the
spectrum does not maintain a thin well-defined dispersion surface, but rather develops into a continuous distribution in ( k,w)\left( \mathbf{k,}\omega\right) -space. The majority of existing measurement systems rely on linear theory for the interpretation of their data, and no measurement
systems are currently able to measure the full spectrum in the open ocean with high accuracy. Nevertheless, there exist a
few low-resolution systems where data may be interpreted within a minimal assumption of a non-restricted ( k,w)\left( \mathbf{k,}\omega\right) -spectrum. The theory is reviewed, and analyses based on conventional spectral analysis as well as a directional wavelet analysis
are carried out on data from a compact laser array at the Ekofisk field in the North Sea. The investigation confirms the strong
impact of the second order spectrum below the spectral peak, but is non-conclusive about the off-set in the support of the
first order spectrum seen in the dynamical simulations. 相似文献
17.
This study not only attempts to justify an equivalent stationary motion model, but also endeavours to illustrate its potentials as an attractive analysis tool. Using 38 ground accelerations recorded on rock sites as data base, this study first demonstrates that the equivalent stationary motions do give average response spectra compatible with real records. This study also shows that through the equivalent stationary model, a set of motions may be defined by specifying the joint distributions of the model parameters. Finally, by converting a relationship between earthquake magnitude and liquefaction potentials of ground motions, this study has derived normalized magnitude-dependent response spectra for rock sites. 相似文献
18.
A theoretically exact relation is presented between the Fourier amplitude spectrum and the elastic input‐energy spectrum. This energy spectrum is computed from the Fourier acceleration amplitude spectrum and the real part of the relative velocity transfer function of the single‐degree‐of‐freedom elastic oscillator. Some accelerometric records collected worldwide are used to prove the solution. It is shown that the relation presented in this work opens the door for a better understanding of the relationship between the input‐energy spectrum and other seismological variables, such as magnitude and focal distance. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
19.
Gian Michele Calvi 《地震工程与结构动力学》2018,47(13):2627-2643
For several decades, seismologists and engineers have been struggling to perfect the shape of design spectra, analyzing recorded signals, and speculating on probabilities. This research effort produced several improvements, for example, suggesting to adopt more than one period to define a spectral shape or proposing different spectral shapes as a function of the return period of the design ground motion. The spectral shapes recommended in most modern codes are driven by considerations on uniform hazard; however, the basic assumption of adopting essentially three fundamental criteria, ie, constant acceleration at low periods, constant displacement at long periods, and constant velocity in an intermediate period range, has never been really questioned. In this opinion paper, the grounds of a constant velocity assumption is discussed and shown to be disputable and not physically based. Spectral shape based on different logics are shown to be potentially consistent with the experimental evidence and to lead to possible differences of 100% in terms of displacement and acceleration demand in the wide intermediate period range that characterizes the vast majority of structures. In this framework, the historical development of linear and nonlinear spectra is critically revisited, proposing a novel original way of defining seismic demand. 相似文献
20.
Eduardo Miranda 《地震工程与结构动力学》1993,22(12):1031-1046
This paper presents a probabilistic approach to the estimation of lateral strengths required to provide an adequate control of inelastic deformations in structures during severe earthquake ground motions. In contrast to a deterministic approach, the approach presented herein accounts explicitly for the variability of the response of non-linear systems due to the inherent uncertainties in the intensity and characteristics of the input excitation by considering the probability distribution of maximum inelastic strength demands. This study is based on the computation of non-linear strength demands of single-degree-of-freedom (SDOF) systems experiencing different levels of inelastic deformation when subjected to 124 recorded earthquake ground motions. Using empirical cumulative distribution functions site-dependent probabilistic non-linear spectra were computed for six probabilities of exceedance of different levels of inelastic deformation. It is concluded that the lateral strength required to control displacement ductility demands is significantly affected by the maximum tolerable inelastic deformation, the system's period of vibration, the local site conditions and the level of risk in exceeding the maximum tolerable deformations. 相似文献