共查询到20条相似文献，搜索用时 109 毫秒
1.
为了在众多参数中挑选其中最有代表性的参数,来解释和反映脉冲型地震动对结构的潜在破坏能力,以338条脉冲型地震动记录作为研究对象,分析地震动参数与中低层结构响应的相关性。选取了14个常用地震动参数,对各地震动参数之间的相关性进行分析,从中选出7个代表性地震动参数;并将脉冲型地震动输入中低层结构模型中计算结构响应,分析代表性地震动参数与结构响应的相关性,与基于非脉冲型地震动的相关性计算结果进行对比。选用了3层和7层2个RC框架结构作为中低层结构代表,其基本周期为0.62s和0.89s。结果表明:对于脉冲型地震动,对于3层结构时与结构响应相关性最好的为EPV,对于7层结构时与结构响应相关性最好的为PGV,因此可以用PGV和EPV作为表征脉冲型地震动对中低层结构潜在破坏能力的参数;而对于非脉冲型地震动,与结构响应相关性最好的参数为PGV,可以用PGV作为表征脉冲型地震动对中低层结构的潜在破坏能力的参数。因此,通过地震动参数来解释和表征脉冲型地震动对结构的破坏能力是可行的。 相似文献
2.
3.
This paper presents a novel approach to identify the pulse-like motions in earthquake recordings that dominate the maximum structural responses over a wide period range. The identification method is based on the congruence relationship between the response spectrum and the dimensionless П-response spectrum established in this study through straightforward dimensional arguments of linear and bilinear SDOF oscillators subject to pulse-like ground motions. By evaluating the geometric match and dislocations of the П-response spectrum of a given waveform with the dimensional response spectrum in bi-logarithm plotting, one can identify the simple pulses and their parameters that match simultaneously the kinematic characteristics and the response spectrum of earthquake recordings that exhibit pulse-like features. The developed pulse identification method has been implemented in a computer program and applied successfully to detect the pulse-like motions in the PEER NGA strong motion database. Both velocity and acceleration pulses potentially due to forward directivity effects in near fault regions are identified. The identified velocity pulses show strong correlation with the seismological parameters. They are subsequently used in regression analysis to derive the empirical scaling laws that relate the directivity pulse parameters to the earthquake magnitude and rupture distance. The study confirms some magnitude scaling laws in literature and demonstrates the accuracy and efficiency of the proposed pulse identification method. 相似文献
4.
长周期地震动的频谱特性是影响长周期结构动力响应的重要因素,目前关于其频谱特征周期参数的研究尚有欠缺.根据长周期地震动的界定方法,选取65条远场长周期地震动和50条近场脉冲型地震动,计算各条地震动的10个频谱特征周期参数,通过分析各周期参数与长周期地震动低频特性指标的相关性和离散性,探讨合适的长周期地震动频谱特征周期表征... 相似文献
5.
Although for many years it was thought that amplitude scaling of acceleration time series to reach a target intensity did not introduce any bias in the results of nonlinear response history analyses, recent studies have showed that scaling can lead to an overestimation of deformation demands with increasing scale factors. Some studies have suggested that the bias can be explained by differences in spectral shape between the response spectra of unscaled and scaled records. On the basis of these studies, some record selection procedures assume that if records are selected using spectral-shape-matching procedures, amplitude scaling does not induce any bias on the structural response. This study evaluates if bias is introduced on lateral displacement demands and seismic collapse risk estimates even when spectral shape is carefully taken into consideration when selecting ground motions. Several single-degree-of-freedom and multiple-degree-of-freedom systems are analyzed when subjected to unscaled and scaled ground motions selected to approximately match the mean and the variance of the conditional spectrum at the target level of intensity. Results show that an explicit consideration of spectral shape is not enough to avoid a systematic overestimation of lateral displacement demands and collapse probabilities as the scale factor increases. Moreover, the bias is observed in practically all cases for systems with strength degradation and it increases with decreasing period and decreasing lateral strength relative to the strength required to remain elastic. Key reasons behind the bias are presented by evaluating input energy, causal parameters, and damaging pulse distributions in unscaled and scaled ground motion sets. 相似文献
6.
Amplitude scaling is commonly used to select ground motions matching a target response spectrum. In this paper, the effect of scaling limits on ground motion selection, based on the conditional spectrum framework, is investigated. Target spectra are computed for four probabilistic seismic hazard cases in Western United States, and 16 ground motion suites are selected using different scaling limits (ie, 2, 5, 10, and 15). Comparison of spectral acceleration distributions of the selected ground motion suites demonstrates that the use of a scaling limit of 2 yields a relatively poor representation of the target spectra, because of the small limit leading to an insufficient number of available ground motions. It is also shown that increasing scaling limit results in selected ground motions with generally increased distributions of Arias intensity and significant duration Ds5-75, implying that scaling limit consideration can significantly influence the cumulative and duration characteristics of selected ground motions. The ground motion suites selected are then used as input for slope displacement and structural dynamic analyses. Comparative results demonstrate that the consideration of scaling limits in ground motion selection has a notable influence on the distribution of the engineering demand parameters calculated (ie, slope displacement and interstory drift ratio). Finally, based on extensive analyses, a scaling limit range of 3 to 5 is recommended for general use when selecting ground motion records from the NGA-West2 database. 相似文献
7.
近场地震的动力特性明显不同于远场地震,因此有必要对结构在近场地震作用下的动力性能展开研究。以上部钢结构-下部混凝土结构这类竖向刚度不同的加层混合结构为研究对象,对其在近场脉冲型地震、近场无脉冲型地震及远场地震作用下的动力响应进行研究。结果表明:在多遇、设防、罕遇地震作用下,近场脉冲型地震会使结构的层间位移角、层间剪力、加速度等动力响应均放大并出现超限的情况,而且都比罕遇地震作用下结构的响应增大更明显;在进行近场区加层混合框架结构的设计和建设时,近场脉冲效应会使结构存在不满足规范的情况,有必要对竖向刚度不同的加层混合结构在近场区的适用性进行深入研究。 相似文献
8.
Ahmer Ali Raffaele De Risi Anastasios Sextos Katsuichiro Goda Zhiwang Chang 《地震工程与结构动力学》2020,49(1):24-50
The increasing number of wind turbines in active tectonic regions has attracted scientific interest to evaluate the seismic vulnerability of offshore wind turbines (OWTs). This study aims at assessing the deformation and collapse susceptibility of 2MW and 5MW OWTs subjected to shallow-crustal pulse-like ground motions, which has not been particularly addressed to date. A cloud-based fragility assessment is performed to quantify the seismic response for a given intensity measure and to assess the failure probabilities for pulse-like and non-pulse-like ground motions. The first-mode spectral acceleration Sa(T1) is found to be an efficient response predictor for OWTs, exhibiting prominent higher-mode behavior, at the serviceability and ultimate conditions. Regardless of earthquake type, it is shown that records with strong vertical components may induce nonlinearity in the supporting tower, leading to potential failure by buckling in three different patterns: (i) at tower base near platform level, (ii) close to tower top, and (iii) between the upper half of the main tower and its top. Type and extent of the damage are related to the coupled excitation of vertical and lateral higher modes, for which tower top acceleration response spectra Sa,i(Top) is an effective identifier. It is also observed that tower's slenderness ratio (l/d), the diameter-to-thickness ratio (d/t), and the rotor-nacelle-assembly mass (mRNA) are precursors for evaluating the damage mode and vulnerability of OWTs under both pulse-like and non-pulse-like ground motion records. 相似文献
9.
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
10.
Fabrizio Mollaioli Andrea Lucchini Yin Cheng Giorgio Monti 《Bulletin of Earthquake Engineering》2013,11(5):1841-1866
Base isolation has become a widely applied technique for protecting buildings located in highly seismic areas. Due to the strongly non-linear constitutive behaviour typical of many isolation devices, the seismic response of base-isolated buildings is usually evaluated through non-linear dynamic analysis. In this type of analysis a suitable set of ground motions is needed for representing the earthquake loads and for exciting the structural model. Many methods can be found in the literature for defining the ground motions. When natural accelerograms are used, the methods mainly differ from each other based on the intensity measures used for scaling the records to the defined earthquake intensity level. Investigations have been carried out for evaluating the predictive capability of the intensity measures used in these methods: while many studies focused on ordinary buildings, only a few focused on base-isolated ones. The objective of this paper is to evaluate the most commonly used intensity measures, which are currently available in the literature, with respect to their capability to predict the seismic response of base-isolated buildings. Selected for the investigation are two frame structures characterized by a different number of storeys and base-isolated with systems having different properties. Two sets of accelerograms, consisting of ordinary and pulse-like near-fault records, are used in the analyses and in the evaluation of the intensity measures. Modified versions of existing intensity measures are also proposed, with the intent of improving the correlations between the considered intensity measures and response quantities. 相似文献
11.
近断层脉冲型地震动作用下隔震结构地震反应分析 总被引：17，自引：5，他引：17
隔震结构在远震场地减震效果良好，但是近断层地震动的明显的长周期速度和位移脉冲运动可能对隔震建筑等长周期结构的抗震性能和设计带来不利影响，需要深入探讨。本文首先讨论近断层地震动的长周期脉冲运动特征，然后以台湾集集地震8条典型近震记录和其它4条常用近震记录以及4条远震记录作为地震动输入，对两幢安装铅芯橡胶隔震支座的钢筋混凝土框架隔震结构进行非线性地震反应时程分析，通过比较探讨了算例计算结果，定量说明隔震结构的近震脉冲效应显著，是隔震设计不容忽视的问题。 相似文献
12.
The accuracy of the three‐dimensional modal pushover analysis (MPA) procedure in estimating seismic demands for unsymmetric‐plan buildings due to two horizontal components of ground motion, simultaneously, is evaluated. Eight low‐and medium‐rise structures were considered. Four intended to represent older buildings were designed according to the 1985 Uniform Building Code, whereas four other designs intended to represent newer buildings were based on the 2006 International Building Code. The median seismic demands for these buildings to 39 two‐component ground motions, scaled to two intensity levels, were computed by MPA and nonlinear response history analysis (RHA), and then compared. Even for these ground motions that deform the buildings significantly into the inelastic range, MPA offers sufficient degree of accuracy. It is demonstrated that PMPA, a variant of the MPA procedure, for nonlinear systems is almost as accurate as the well‐known standard response spectrum analysis procedure is for linear systems. Thus, for practical applications, the PMPA procedure offers an attractive alternative to nonlinear RHA, whereby seismic demands can be estimated directly from the (elastic) design spectrum. In contrast, the nonlinear static procedure specified in the ASCE/SEI 41‐06 Standard is demonstrated to grossly underestimate seismic demands for some of the unsymmetric‐plan buildings considered. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
13.
The selection of representative input ground motions (IGMs) is important for a proper nonlinear response time history analysis (NLRHA) of modern structures. The prevailing IGM selection procedure requires that the response spectra of selected ground motions are matched with the code-specified design spectra, while the effect of the frequency contents combination in the time domain on the multimode interactions is not considered. Ignoring the effect of the frequency contents combination in the time domain of IGMs may cause significant variations in the analysis results for selected IGMs, although they are matched to the same design spectrum. In this paper, a modal-based ground motion selection (MGMS) procedure is proposed as a supplement to spectrum matching-based IGM selection procedures for selecting proper IGMs that can sufficiently induce the multimode interactions. In the proposed procedure, three equivalent single-degree-of-freedom (ESDOF) systems are developed by pushover analysis. NLRHA is then conducted for these ESDOF systems with a set of 20 seed IGMs chosen by the spectrum-matching–based selection procedure. Finally, seven IGMs are selected from the seed IGMs for NLRHA in the full structural model. To verify MGMS, seismic demands of high-rise buildings were computed by NLRHA with seven MGMS-selected IGMs, seven IGMs with closest spectrum matching, and groups of seven randomly selected IGMs derived from three different sets of 20 seed IGMs. The computed seismic demands with MGMS-IGMs show very good agreement with the mean demands determined using the whole set of seed IGMs, while the deviation is much lesser compared with those groups of randomly selected IGMs. 相似文献
14.
A spectral-velocity-based combination-type ground motion intensity measure (IM), which is inspired by the superior sensitivity of spectral velocity to structural response compared with other two spectral quantities, is proposed for super high-rise building structures with the consideration of the characteristics of ground motions and structures themselves. Two super high-rise buildings with typical frame/core-tube/outrigger lateral resisting system and a wide range of structural height (H = 258 m~660 m) are deliberately selected to identify the correlation between the maximum inter-story drift ratio and nineteen IMs developed in recent decade together with the proposed IM, with sixty chosen far-field and near-field pulse-like ground motions. With the suggested optimal number of lower vibration modes and corresponding combination factors, the efficiency, sufficiency and the scaling robustness of the proposed IM is further demonstrated. In addition, the relative sufficiency measures of other IMs with respect to the proposed IM are investigated. The results from the study indicate that, the proposed IM is believed, from the standpoint of efficiency, sufficiency, relative sufficiency measure and scaling robustness, to be a more specialized and desirable tool for super high-rise buildings, either for far-field or near-field ground motions. 相似文献
15.
Ground motion selection for simulation‐based seismic hazard and structural reliability assessment 
下载免费PDF全文
下载免费PDF全文 This paper examines four methods by which ground motions can be selected for dynamic seismic response analyses of engineered systems when the underlying seismic hazard is quantified via ground motion simulation rather than empirical ground motion prediction equations. Even with simulation‐based seismic hazard, a ground motion selection process is still required in order to extract a small number of time series from the much larger set developed as part of the hazard calculation. Four specific methods are presented for ground motion selection from simulation‐based seismic hazard analyses, and pros and cons of each are discussed via a simple and reproducible illustrative example. One of the four methods (method 1 ‘direct analysis’) provides a ‘benchmark’ result (i.e., using all simulated ground motions), enabling the consistency of the other three more efficient selection methods to be addressed. Method 2 (‘stratified sampling’) is a relatively simple way to achieve a significant reduction in the number of ground motions required through selecting subsets of ground motions binned based on an intensity measure, IM. Method 3 (‘simple multiple stripes’) has the benefit of being consistent with conventional seismic assessment practice using as‐recorded ground motions, but both methods 2 and 3 are strongly dependent on the efficiency of the conditioning IM to predict the seismic responses of interest. Method 4 (‘generalized conditional intensity measure‐based selection’) is consistent with ‘advanced’ selection methods used for as‐recorded ground motions and selects subsets of ground motions based on multiple IMs, thus overcoming this limitation in methods 2 and 3. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
Spectral shape,epsilon and record selection 总被引：4，自引：0，他引：4
Selection of earthquake ground motions is considered with the goal of accurately estimating the response of a structure at a specified ground motion intensity, as measured by spectral acceleration at the first‐mode period of the structure, Sa(T1). Consideration is given to the magnitude, distance and epsilon (ε) values of ground motions. First, it is seen that selecting records based on their ε values is more effective than selecting records based on magnitude and distance. Second, a method is discussed for finding the conditional response spectrum of a ground motion, given a level of Sa(T1) and its associated mean (disaggregation‐based) causal magnitude, distance and ε value. Records can then be selected to match the mean of this target spectrum, and the same benefits are achieved as when records are selected based on ε. This mean target spectrum differs from a Uniform Hazard Spectrum, and it is argued that this new spectrum is a more appropriate target for record selection. When properly selecting records based on either spectral shape or ε, the reductions in bias and variance of resulting structural response estimates are comparable to the reductions achieved by using a vector‐valued measure of earthquake intensity. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
17.
针对钢筋混凝土高层建筑抗震时程分析输入地震波选择问题,以《建筑抗震设计规范》（GB 50011-2016）设计谱为目标谱,将满足谱匹配原则的加权调幅选波方法与国内学者建议的其它输入地震波选择方法进行了对比研究。以3栋钢筋混凝土高层建筑（15层、30层和44层）为实例,针对8度罕遇地震作用和Ⅱ类场地条件,将上述方法建议的各7条地震波输入结构进行弹塑性时程分析。以结构最大层间位移角均值沿楼层分布为比较参数。结果表明:加权调幅法可用于钢筋混凝土高层建筑抗震时程分析,可以较好地降低结构地震反应均值的离散性。在8度罕遇地震作用条件下,以不同学者建议选择的地震波为输入,高层建筑时程分析结果仍呈现出较大的不同。 相似文献
18.
In this study, attempts are made to investigate the effects of inertial soil–structure interaction (SSI) on damping coefficients subjected to pulse-like near-fault ground motions. To this end, a suit of 91 pulse-like near-fault ground motions is adopted. The soil and superstructure are idealized employing cone model and single-degree-of-freedom (SDOF) oscillator, respectively. The results demonstrate that soil flexibility reduces and amplifies the damping coefficients for structural viscous damping levels higher and lower than 5%, respectively. The coefficients reach one for both acceleration and displacement responses in cases of dominant SSI effects. The effect of structure dimensions on damping confidents are found insignificant. Moreover, damping coefficients of displacement responses are higher than those of acceleration responses for both fixed-base and flexible-base systems. Evaluation of damping correction factor introduced by FEMA 440 shows its inefficiency to predict acceleration response of soil–structure systems under pulse-like near-fault ground motions. Soil flexibility makes the damping correction factor of moderate earthquakes more pronounced and a distinctive peak value is reported for cases with dominant SSI effects. 相似文献
19.
Evaluation of equivalent lateral force procedure in estimating seismic isolator displacements 总被引：1，自引：0，他引：1
Simplified methods of analysis described in codes and specifications for seismically isolated structures are always used either directly in special cases or for checking the results of nonlinear response history analysis (RHA). In this study, the maximum isolator displacements and base shears determined by nonlinear RHA are compared with those determined by the equivalent lateral force (ELF) procedure in order to assess the accuracy of the simplified method in the case of earthquakes with near field characteristics. Features of this study are that the ground motions used in analysis are selected and scaled using contemporary concepts and that the ground excitation is considered bi-directional. It is shown that the simplified method provides acceptably accurate predictions of shear isolator displacements and shear forces for a range of isolator properties and ground motions representative of stiff and soft soil conditions. 相似文献