共查询到20条相似文献，搜索用时 31 毫秒
1.
The paper presents a computationally efficient algorithm to integrate a probabilistic, non-Gaussian parameter estimation approach for nonlinear finite element models with the performance-based earthquake engineering (PBEE) framework for accurate performance evaluations of instrumented civil infrastructures. The algorithm first utilizes a minimum variance framework to fuse predictions from a numerical model of a civil infrastructure with its measured behavior during a past earthquake to update the parameters of the numerical model that is, then, used for performance prediction of the civil infrastructure during future earthquakes. A nonproduct quadrature rule, based on the conjugate unscented transformation, forms an enabling tool to drive the computationally efficient model prediction, model-data fusion, and performance evaluation. The algorithm is illustrated and validated on Meloland Road overpass, a heavily instrumented highway bridge in El Centro, CA, which experienced three moderate earthquake events in the past. The benefits of integrating measurement data into the PBEE framework are highlighted by comparing damage fragilities of and annual probabilities of damages to the bridge estimated using the presented algorithm with that estimated using the conventional PBEE approach. 相似文献
2.
Brendon A. Bradley 《地震工程与结构动力学》2013,42(11):1717-1729
The last decade of performance‐based earthquake engineering (PBEE) research has seen a rapidly increasing emphasis placed on the explicit quantification of uncertainties. This paper examines uncertainty consideration in input ground‐motion and numerical seismic response analyses as part of PBEE, with particular attention given to the physical consistency and completeness of uncertainty consideration. It is argued that the use of the commonly adopted incremental dynamic analysis leads to a biased representation of the seismic intensity and that when considering the number of ground motions to be used in seismic response analyses, attention should be given to both reducing parameter estimation uncertainty and also limiting ground‐motion selection bias. Research into uncertainties in system‐specific numerical seismic response analysis models to date has been largely restricted to the consideration of ‘low‐level’ constitutive model parameter uncertainties. However, ‘high‐level’ constitutive model and model methodology uncertainties are likely significant and therefore represent a key research area in the coming years. It is also argued that the common omission of high‐level seismic response analysis modelling uncertainties leads to a fallacy that ground‐motion uncertainty is more significant than numerical modelling uncertainty. The author's opinion of the role of uncertainty analysis in PBEE is also presented. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
以某典型的20层钢筋混凝土框架剪力墙结构作为研究对象,研究基于性能的RC框架剪力墙结构易损性分析方法。首先选择合适的地震动记录,以0.2g为步长进行调幅后,建立300个结构-地震动样本空间,并确定结构损伤指标和性能参数;然后应用增量动力分析方法计算结构的地震动力响应,选择基本周期加速度反应谱为地震动参数,以研究结构反应的不确定性,并深入分析地震动参数与结构地震需求参数的关系;在此基础上,建立该结构基于加速度反应谱的易损性曲线进行结构易损性分析与评估。结果表明：随着地震动强度的增大,IDA曲线由单调增加变为非单调增加,分位曲线（16%,50%和84%）可以准确地衡量结构的性能;框剪结构在地震作用下的抗震性能表现良好,随着地震强度的增长,各性能超越概率大小的增长速度是不同的。 相似文献
4.
A method to combine probabilistic seismic hazard analysis and stochastic earthquake motion models is presented. A set of parameters characterizing stochastic earthquake motion models is determined on a consistent probabilistic basis. The method proposed herein consists of two steps. First, the ground motion intensity is determined in the context of the conventional hazard curve technique. Next, other ground motion parameters such as duration, predominant frequency and spectral shape parameters are determined as conditional means corresponding to the annual probability of exceedance for the ground motion intensity. Some example applications are presented. 相似文献
5.
In performance-based seismic design, as adopted by several building codes worldwide, the structural performance is verified against ground motions that have predetermined exceedance return periods at the site of interest. Such a return period is evaluated by means of probabilistic seismic hazard analysis (PSHA), and the corresponding ground motion is often represented by the uniform hazard spectrum (UHS). The structural performance for ground motions larger than those considered in this design approach is, typically, not explicitly controlled under the assumption that they are sufficiently rare. On one hand, this does not achieve uniform safety at sites characterized by different design ground motions corresponding to the same return period; on the other hand, exceedances of the design spectra are systematically observed over large areas, for example in Italy. The latter issue is because of the nature of UHS, the exceedance of which is likely-to-almost-certain when the construction site is in the epicentral area of moderate-to-high magnitude earthquakes (ie, the design spectrum may be not conservative at these locations), especially if PSHA is based on seismic source zones. The former is partially because of the systematic difference of ground motions for return periods larger than the design one at the different sites. Quantification of the expected ground motion given the exceedance of the design ground motions (ie, the recently introduced as the expected peak-over-threshold or POT) can be of help in quantitatively assessing these issues. In the study, a procedure to compute the POT distribution is derived first; second, POT spectra are introduced and used to help understanding why and how seismic structural reliability of code-conforming structures decreases as the seismic hazard of the site increases; third, expected and 95th percentile POT maps are shown for Italy to discuss how much high hazard sites are exposed to much larger peak-over-threshold with respect to mid-hazard and low-hazard sites; finally the POT is discussed with respect to the slope of the hazard curve (in log-log scale) at the threshold, a known proxy for ground motion beyond design. All data presented in the maps are made available for the interested reader as a supplemental archive. 相似文献
6.
Ground‐motion intensity and damage map selection for probabilistic infrastructure network risk assessment using optimization 
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下载免费PDF全文 In many parts of the world, earthquakes threaten regional infrastructure systems. For modeling risk using stochastic earthquake catalogs, random variables include rupture location and the damage state of different components. Thus, there is an infinite set of possible damage maps that a risk modeler could evaluate in an event‐based probabilistic loss model. Even a finite but large number of damage maps may not be practical, because many network performance measures are computationally expensive. Here, we show a computationally efficient method for selecting a subset of damage maps, corresponding ground‐motion intensity maps, and associated occurrence rates that reasonably estimates the full distribution of the ground‐motion intensity and a target performance measure using optimization. The method chooses a subset of maps and associated annual rates of occurrence that minimizes the error in estimating the distribution of a network performance measure as well as the marginal distributions of ground‐motion intensity exceedance. The joint distribution of the ground‐motion intensity is implicitly included in the objective function of the optimization problem via the network performance measure. We then show how to tune the optimization parameters based on consistency checks related to the network performance measure and the ground‐motion hazard. We illustrate the proposed method with a case study of the San Francisco Bay Area road network to estimate the exceedance curve of the average percentage change in morning commute trip time. This work facilitates expanded and risk‐consistent studies of the impacts of infrastructure networks on regional seismic risk and resiliency. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
Incorporating intensity bounds for assessing the seismic safety of structures: Does it matter? 下载免费PDF全文
下载免费PDF全文 The closed‐form solution for assessing the proportion of the mean annual frequency of limit‐state exceedance as a function of integration limits is introduced, in order to study whether or not the mean annual frequency of limit‐state exceedance is overestimated if the lower and(or) upper integration limit of the risk equation are(is) not selected in a physically consistent manner. Simple formulas for assessing the threshold value of the lower and upper integration limits are also derived. These formulas can be used to quickly assess the significant range of ground motion intensity that affects the mean annual frequency of limit‐state exceedance. It is shown that the threshold values of the integration limits depend on the median intensity causing a limit‐state, the corresponding dispersion and the slope of the hazard curve in the log domain. For several reinforced concrete buildings located in a region with moderate seismicity, it is demonstrated that the mean annual frequency of collapse can be significantly overestimated when assessed by integrating the risk equation over the entire range of ground motion intensity. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
Ludovica Elefante Fatemeh JalayerIunio Iervolino Gaetano Manfredi 《Soil Dynamics and Earthquake Engineering》2010
The results of seismic hazard disaggregation can be used to assign relative weights to a given ground motion record based on its corresponding magnitude, distance and deviation from the ground motion prediction model (epsilon) in order to make probability-based seismic assessments using non-linear dynamic analysis. In this paper, the implications of using the weighted ground motion records are investigated in terms of the mean annual frequency of exceedance of the critical component-based demand to capacity ratio in an existing reinforced concrete structure using both the peak ground acceleration and the first-mode spectral acceleration as intensity measures. It is demonstrated how site-specific seismic hazard disaggregation can be used in order to obtain the conditional probability distribution for a relevant ground motion characteristic given the chosen intensity measure. Distinguished by the amount of structural analysis required, two alternative non-linear dynamic analysis procedures, namely the cloud and the stripes method are implemented. The weighted cloud and the weighted stripes methods are then introduced as analysis procedures which modify the structural response to the selected ground motion records by employing the information provided from the seismic hazard analysis. It is demonstrated that the resulting annual frequencies based on weighted records are comparable to those obtained by using vector-valued intensity measures, while requiring less computational effort. 相似文献
9.
Seismic hazard disaggregation in performance‐based earthquake engineering: occurrence or exceedance? 下载免费PDF全文
下载免费PDF全文 Seismic hazard disaggregation is commonly used as an aid in ground‐motion selection for the seismic response analysis of structures. This short communication investigates two different approaches to disaggregation related to the exceedance and occurrence of a particular intensity. The impact the different approaches might have on a subsequent structural analysis at a given intensity is explored through the calculation of conditional spectra. It is found that the exceedance approach results in conditional spectra that will be conservative when used as targets for ground‐motion selection. It is however argued that the use of the occurrence disaggregation is more consistent with the objectives of seismic response analyses in the context of performance‐based earthquake engineering. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
The last decade or so has seen the development of refined performance-based earthquake engineering(PBEE) approaches that now provide a framework for estimation of a range of important decision variables,such as repair costs,repair time and number of casualties. This paper reviews current tools for PBEE,including the PACT software,and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore,proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed,highlighting needs for future research. To illustrate the potential of the methodology,performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework,applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations. 相似文献
11.
The last decade or so has seen the development of refined performance-based earthquake engineering (PBEE) approaches that now provide a framework for estimation of a range of important decision variables, such as repair costs, repair time and number of casualties. This paper reviews current tools for PBEE, including the PACT software, and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore, proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed, highlighting needs for future research. To illustrate the potential of the methodology, performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework, applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations. 相似文献
12.
大多数地震破裂面源检测方法都是通过简化地震震源,将地震震源表示成线源或者点源,无法有效描述地震带地震破裂面源产状和大小,不适用地震震级较大的情况下地震危险性检测。因此提出基于数学建模的潜在地震破裂面源检测方法,在地震震级较大时仍能检测出地震危险性概率。选取适宜的地震基岩水平峰值加速度衰减关系,分析地震震级、破裂长度、破裂宽度相互关系,确定地震引起的潜在地震破裂面源大小,计算给定地震动小于在场点处产生地震动的概率,将该概率同地震动加速度衰减关系结合,得到地震动年超越概率,分析地震危险性。经过实验检测发现,所提方法检测出的年超越概率与峰值加速度、最大震级有关,该概率能精准表示地震带地震破裂面源产状和大小,说明该方法检测地震危险性是合理的。 相似文献
13.
基于改进云图法的结构概率地震需求分析 总被引：2，自引：0，他引：2
概率地震需求分析是美国太平洋地震工程研究中心(Pacific Earthquake Engineering ResearchCenter,PEER)提出的新一代"性能化地震工程(Performance-Based Earthquake Engineering,PBEE)"理论框架的重要一环。传统的概率地震需求分析方法称为"云图法",这种方法针对确定性结构进行一系列地震动作用下的非线性动力分析,从而得到地震动强度参数与结构地震需求的"云图"。然而,传统的云图法只能考虑地震动的不确定性,而无法考虑结构的不确定性。为此,结合拉丁超立方体抽样技术,提出一种能综合考虑地震动不确定性和结构不确定性的改进云图法,并将传统的概率地震需求分析内容拓展为概率地震需求模型、概率地震需求易损性分析、概率地震需求危险性分析三个层次。以一榀五层三跨钢筋混凝土框架结构为例,分别采用传统云图法和改进云图法对其进行概率地震需求分析,得到了该结构的概率地震需求模型、地震需求易损性曲线和地震需求危险性曲线。分析结果表明:提出的方法可以有效地考虑地震动与结构的不确定性,避免不考虑结构的不确定性而低估结构的地震风险性。 相似文献
14.
Sensitivity of PSHA results to ground motion prediction relations and logic-tree weights 总被引：7，自引：0，他引：7
Fabio Sabetta Antonio Lucantoni Hilmar Bungum Julian J. Bommer 《Soil Dynamics and Earthquake Engineering》2005,25(4):317-329
Epistemic uncertainty in ground motion prediction relations is recognized as an important factor to be considered in probabilistic seismic hazard analysis (PSHA), together with the aleatory variability that is incorporated directly into the hazard calculations through integration across the log-normal scatter in the ground motion relations. The epistemic uncertainty, which is revealed by the differences in median values of ground motion parameters obtained from relations derived for different regions, is accounted for by the inclusion of two or more ground motion prediction relations in a logic-tree formalism. The sensitivity of the hazard results to the relative weights assigned to the branches of the logic-tree, is explored through hazard analyses for two sites in Europe, in areas of high and moderate seismicity, respectively. The analyses reveal a strong influence of the ground motion models on the results of PSHA, particularly for low annual exceedance frequencies (long return periods) and higher confidence levels. The results also show, however, that as soon as four or more relations are included in the logic-tree, the relative weights, unless strongly biased towards one or two relations, do not significantly affect the hazard. The selection of appropriate prediction relations to include in the analysis, therefore, has a greater impact than the expert judgment applied in assigning relative weights to the branches of the logic-tree. 相似文献
15.
土的动剪切模量比和阻尼比是土层地震反应分析、工程场地地震安全性评价和地震小区划工作中的必备参数,但其不确定性显著,对地震动和抗震设计影响很大。本文以我国常规土类动剪切模量比和阻尼比与剪应变非线性关系试验为基础,研究考虑这两个动力参数变异性下其超越概率的计算方法。方法包括了试验数据的整理、超越概率的计算以及两个动力参数和超越概率关系模拟等几个步骤,最后给出了我国常规土类动剪切模量比和阻尼比超越概率的计算公式,为我国基于概率和可靠度思想的工程地震安全风险评估提供了一定基础。 相似文献
16.
在基于性能的地震工程学(PBEE)中,建立概率地震需求模型(PSDM)时需要对桥梁结构的工程需求参数(EDP)进行概率估计。其中,强地面运动参数(IM)的选择对EDP的概率估计影响很大,因此需要正确选择IM。分别采用目前最广泛使用的结构第一模态周期弹性谱加速度(5%阻尼比)Sa(T1,5%)和峰值地面加速度PGA作为IM,选择实际地震波并进行合理的调值,对一座钢筋混凝土桥墩进行IDA分析,其计算结果表明:对于不同性质EDP的概率估计值,以PGA作为IM计算所得的结果明显偏于非保守,且离散度一般也更大。说明可以针对不同性质的EDP,根据地面运动强度的大小,选择不同的IM,通过合理的调值对EDP进行概率估计,可以更加精确、高效地建立PSDM。 相似文献
17.
工程场地的设计地震动参数,目前多用概率地震危险性分析的方法给出。场地的地震基本烈度以设计基准期T=50年、加速度超越概率P=0.1的标准确定。本文根据广东省数地地震危险性分析结果结合我国常见的砖混结构的地震动参数的优化决策,认为上述标准宜取为T=50年、P=0.05—0.1。 相似文献
18.
计算机仿真模拟设定地震断层动态破裂传播和近断层强地表运动响应的结果表明， 对于特征地震而言，近断层附近的地表运动特征与断层破裂传播的方向性有着强烈的依赖关系. 当场地（观测点）至断层的距离给定时，正向于破裂传播方向的场地（场地A）的地表质点运动（位移、速度、加速度），远远大于震中附近（场地B）和反向于破裂传播方向的场地（场地C）的地表质点运动，而且沿断层垂直分量所辐射的SH波的传播起到了主导作用. 对应于场地A，B和C，统计分析结果表明，峰值加速度的几何平均值之比为2.15:1.5:1， 而且各自的均方差分别为0.12, 0.11和0.13. 如果将所得的研究结果应用于概率地震危险性分析中，对于较低的年超越频度，近断层附近的地表峰值加速度的估算值可下降15%~30%. 因此，考虑到断层破裂传播方向性对地表运动的影响，区域衰减曲线的回归分析模型应该给予恰当的修正. 相似文献
19.
利用基于性能的结构可靠度分析方法,对基础隔震钢筋混凝土框剪结构进行分析研究。选取20条实际地震动记录,以0.2g为步长对结构地震动参数PGA进行调幅后,建立了140个结构-地震动样本空间。选取上部结构的最大层间位移角、隔震层位移为量化指标,对每一个样本进行动力非线性时程分析后,将结构响应进行统计得到结构在各地震动强度下超越极限破坏状态的概率,将其绘制成基础隔震钢筋混凝土框剪结构的易损性曲线并利用整体可靠度方法分析结构发生倒塌的可靠度指标。该方法直观地反映了结构发生倒塌的概率,为结构的地震损失评估提供依据。 相似文献
20.
软土地基深开挖对场地设计地震动的影响 总被引：16，自引：3，他引：13
本文根据南京河西地区所处的地震地质环境、地震活动环境及基岩地震动衰减规律,在场址区地震危险性分析基础上确定该地区的基岩地震动参数,并选取河西地区某个典型工程场地,根据场地上的静、动力性能参数的测试结果,进行场地上层地震反应分析,研究软土地基条件下地基深开挖场地的地震动效应及其对场地设计地震动参数的影响．文中给出了设计基准期为５０年及１００年时对应不同抗震设防水准的设计地震动参数,该结果对河西地区其它高层建筑的抗震设计也有一定的参考价值． 相似文献