共查询到19条相似文献，搜索用时 406 毫秒
1.
易损性分析是隧道工程领域防震减灾研究的重要方法。首先,详细综述了国内外隧道地震易损性研究历史与现状;其次,归纳了国内外隧道地震易损性分析主要方法,并总结了各种方法的实际适用性;接着,提出了隧道地震易损性评估步骤,并且讨论了以数值模拟为主要手段的理论易损性曲线建立中的3个关键内容:(1)输入参数确定;(2)破坏状态分级;(3)相关不确定性参数计算;最后,指出该领域一些亟待解决的问题和未来研究发展的方向。结果表明:隧道地震易损性分析能通过考虑相关不确定性因素,反映了隧道在地震荷载作用下的性能,有利于未来的风险评估和损失估算,对基于性能的隧道抗震设计的发展具有重要意义。 相似文献
2.
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
3.
为考虑核电厂结构参数不确定对结构地震易损性的影响,基于一次二阶矩法(First-Order Second-Moment, FOSM)进行地震易损性分析。以核电结构中混凝土材料的密度、弹性模量,泊松比和抗拉强度为不确定参数,建立有限元模型,并与试验结果对比,以验证模型的准确性。基于有限元数值模拟方法,通过增量动力法计算核电厂模型在多条地震记录下不同峰值加速度的动力响应,同时基于FOSM得到参数不确定下的对数标准差,进而得到核电厂结构考虑参数不确定的地震易损性曲线。结果表明,结构参数的不确定对核电结构有一定的影响,未考虑参数不确定的地震易损性结果会低估结构的失效概率。该方法可为核电结构基于参数不确定下的易损性分析提供一定的理论依据与实用价值。 相似文献
4.
《世界地震工程》2017,(4)
基于地震工程模拟平台Open SEES,研究了型钢混凝土(SRC)框架的数值建模方法。根据试验结果对比了3种不同非线性梁柱单元模型的计算效果,确定了最优单元模型。基于Open SEES平台和增量动力分析(IDA)方法研究了型钢混凝土框架结构的地震易损性。设计了3个具有不同柱梁抗弯承载力之比的结构,对其进行IDA分析,获得了各模型的抗震能力曲线。根据结构抗震能力曲线,求解了结构的地震易损性曲线,得到了结构在地震作用下各性态点的超越概率。对场地地震危险性进行分析,获得了场地地震危险性概率模型。基于结构地震易损性曲线及场地地震危险性概率模型,计算了结构各性态点的年平均超越概率。结果表明:柱梁抗弯承载力之比对计算结果的影响显著,随着柱梁抗弯承载力之比的增大,结构在特定地震动作用下倒塌的概率呈减小趋势。 相似文献
5.
地震破坏状态概率分析是抗震结构最优设防水平决策与全寿命优化设计的关键问题之一,作者们曾根据"三水准"设防原则和地震烈度的危险性分析结果提出了二种实用分析方法.本文建立了结构破坏状态概率分析的地震易损性理论基础,提出了极限状态地震易损性和破坏状态地震易损性的概念.从地震易损性理论的角度,对二种地震破坏状态概率简化分析方法进行了深入分析,指出第1种方法是一种考虑结构宏观抗震能力不确定性的半理论半经验易损性分析方法,而第2种方法则是一种不考虑结构宏观抗震能力不确定性的简化易损性分析方法,根据地震破坏状态概率的计算结果对二种方法进行了对比分析,并提出了相关的建议. 相似文献
6.
多层住宅砖房的地震易损性分析 总被引：5，自引：2，他引：5
本文采用概率方法借助于拉丁超立方采样技术和非线性地震反应过程分析对多层住宅砖房的地震易损性进行分析。其分析样本是根据多层住宅砖房目前常用设计参数值的范围选定参数的代表值，并由这些代表值构成的；分析中考虑了地震荷载、结构反应和结构承载力的不确定性。易损性曲线分别对五个不同结构破坏程度的极限状态给出。 相似文献
7.
增量动力分析（IDA）作为动力形式的静力推覆法,被广泛应用于建筑结构的抗震能力分析和性能评估中,但其在土建筑遗址地震易损性分析中的应用甚少。基于IDA方法尝试对交河故城塔林区金刚宝座式塔土建筑遗址进行在地震作用下的易损性和抗震能力分析,以谱加速度Sa（T1,5%）作为地震动强度指标,最大层间位移角θmax作为结构损伤指标进行IDA分析,得到土建筑遗址在一系列调幅地震动作用下的IDA曲线、地震需求概率模型和易损性曲线,计算出模型的倒塌率和CMR值。通过以上分析得出金刚宝座式塔的易损性和抗震能力,为今后土建筑遗址抗震保护提供理论基础和分析思路。 相似文献
8.
通过有限元方法进行非线性动力时程分析获取解析的易损性曲线,计算量大且耗时。本文采用一种简化的计算方法,即基于单自由度的等效线性化模型,对钢筋混凝土框架结构进行地震易损性分析,并研究了该方法在结构高度上的适用性。通过选用5种典型的等效线性化模型对3栋不同高度的钢筋混凝土框架结构进行增量动力分析（IDA）,得到了不同高度的结构在不同强度地震作用下结构的反应和易损性,并与OpenSees程序的计算结果进行对比,研究了等效线性化模型应用于RC框架结构易损性分析在高度上的适用性。分析结果表明:对于10层及以下的框架结构,基于单自由度的等效线性化模型在结构地震易损性分析中具有较好的适用性;对于更高层数的结构,由于高阶振型反应对整体结构反应的影响增大,基于单自由度等效线性化模型的易损性分析结果会出现明显的偏差。 相似文献
9.
设计1个20层SRC框架核心筒结构模型,考虑地震的随机性和结构材料的不确定性,采用拉丁超立方体抽取结构-地震动样本,之后对其进行增量动力分析（IDA）,以第1周期谱加速度为强度指标,最大层间位移角为结构需求,定义4个性能水平,研究该结构的易损性。通过引入群体结构震害评估中易损性指数的概念,计算多遇、设防和罕遇地震下的易损性指数。结果表明:以易损性指数作为评价指标,该结构在多遇地震作用下,处于轻微破坏状态;在设防地震作用下,处于中等破坏状态;在罕遇地震作用下,结构处于严重破坏状态。可认为依据我国抗震规范设计的SRC框架核心筒结构能够满足"小震不坏"、"中震可修"和"大震不倒"的抗震设防目标。 相似文献
10.
为研究基于有限元模型确认的门式刚架结构的地震易损性,依据功率谱法对一实测门式刚架结构在环境激励下的时程响应数据进行时频转换,提取结构特征值作为有限元模型确认的目标函数,通过复形法多次迭代,更新有限元模型结构。对确认后的有限元模型进行增量动力分析,得到结构地震易损性曲线,并进一步基于β分布构建震害指数表达式,绘制震害优化比曲线,分析附着黏滞阻尼器结构的抗震性能。结果表明：有限元模型确认理论可减小结构参数不确定性带来的误差,使有限元模型结构性能状态贴近真实结构;附着黏滞阻尼器结构相比初始结构有更好的抗震表现,结构的抗震能力可提升约30%。 相似文献
11.
Fragility curves constitute the cornerstone in seismic risk evaluations and performance-based earthquake engineering. They describe the probability of a structure to experience a certain damage level for a given earthquake intensity measure, providing a relationship between seismic hazard and vulnerability. In this paper a numerical approach is applied to derive fragility curves for tunnel shafts built in clays, a component that is found in several critical infrastructure such as urban metro networks, airport facilities or water and waste water projects. The seismic response of a representative tunnel shaft is assessed using tridimensional finite difference non-linear analyses carried out with the program FLAC3D, under increasing levels of seismic intensity. A hysteretic model is used to simulate the soil non-linear behavior during the seismic event. The effect of soil conditions and ground motion characteristics on the soil-structure system response is accounted for in the analyses. The damage is defined based on the exceedance of the concrete wall shaft capacity due to the developed seismic forces. The fragility curves are estimated in terms of peak ground acceleration at a rock or stiff soil outcrop, based on the evolution of damage with increasing earthquake intensity. The proposed fragility models allows the characterization of the seismic risk of a representative tunnel shaft typology and soil conditions considering the associated uncertainties, and partially fill the gap of data required in performing a risk analysis assessment of tunnels shafts. 相似文献
12.
In this paper a numerical approach is proposed for the construction of fragility curves for shallow metro tunnels in alluvial deposits, when subjected to transversal seismic loading. The response of the tunnel is calculated under quasi static conditions applying the induced seismic ground deformations which are calculated through 1D equivalent linear analysis for an increasing level of seismic intensity. The results of the present numerical analyses are compared with selected closed form solutions, highlighting the limitations of the latter, while indicative full dynamic analysis are performed in order to validate the results of the quasi-static method. The proposed approach allows the evaluation of new fragility curves considering the distinctive features of the tunnel geometries and strength characteristics, the input motion and the soil properties as well as the associated uncertainties. The comparison between the new fragility curves and the existing empirical ones highlights the important role of the local soil conditions, which is not adequately taken into account in the empirical curves. 相似文献
13.
Faulting is one type of permanent ground displacement (PGD); tunnels are at the risk of damage when they are susceptible to faulting. The present study proposes an experimental approach to create the fragility curves for shallow segmental tunnels in alluvial deposits subjected to normal surface faulting. Centrifuge testing was carried out in order to achieve this purpose. The proposed approach allows evaluation of new fragility curves considering the distinctive features of tunnel geometry and fault specifications. The comparison between the new fragility curves and the existing empirical curves was discussed as well. Compared to tunnels in rock, tunnels in alluvial deposits are more susceptible to failure because of different mechanisms of collapse into tunnel at large exerted PGD. 相似文献
14.
Seismic fragility analysis of highway bridges considering multi-dimensional performance limit state 总被引：1，自引：0，他引：1
Fragility analysis for highway bridges has become increasingly important in the risk assessment of highway transportation networks exposed to seismic hazards. This study introduces a methodology to calculate fragility that considers multi-dimensional performance limit state parameters and makes a first attempt to develop fragility curves for a multi-span continuous (MSC) concrete girder bridge considering two performance limit state parameters: column ductility and transverse deformation in the abutments. The main purpose of this paper is to show that the performance limit states, which are compared with the seismic response parameters in the calculation of fragility, should be properly modeled as randomly interdependent variables instead of deterministic quantities. The sensitivity of fragility curves is also investigated when the dependency between the limit states is different. The results indicate that the proposed method can be used to describe the vulnerable behavior of bridges which are sensitive to multiple response parameters and that the fragility information generated by this method will be more reliable and likely to be implemented into transportation network loss estimation. 相似文献
15.
通信铁塔的地震易损性研究是通信系统震后灾害评估和预测的基础工作之一,但在以往的通信系统地震灾害评估研究中,这一工作被忽略了。在对北方某城市大量通信铁塔进行调研的基础上,选取了3个典型通信铁塔（50 m高四方塔、30 m高四方塔和50 m高单管塔）作为研究对象,采用有限元软件ABAQUS建立了数值模型;通过对3个铁塔的静力推覆分析,得到了处于不同损伤状态下的损伤指标数值;通过增量动力分析,得到了3个通信铁塔的抗震性能和地震易损性曲线,为通信系统地震灾害评估和预测提供参考。 相似文献
16.
The seismic fragility of a system is the probability that the system enters a damage state under seismic ground motions with specified characteristics. Plots of the seismic fragilities with respect to scalar ground motion intensity measures are called fragility curves. Recent studies show that fragility curves may not be satisfactory measures for structural seismic performance, since scalar intensity measures cannot comprehensively characterize site seismicity. The limitations of traditional seismic intensity measures, e.g., peak ground acceleration or pseudo-spectral acceleration, are shown and discussed in detail. A bivariate vector with coordinates moment magnitude m and source-to-site distance r is proposed as an alternative seismic intensity measure. Implicitly, fragility surfaces in the (m, r)-space could be used as graphical representations of seismic fragility. Unlike fragility curves, which are functions of scalar intensity measures, fragility surfaces are characterized by two earthquake-hazard parameters, (m, r). The calculation of fragility surfaces may be computationally expensive for complex systems. Thus, as solutions to this issue, a bi-variate log-normal parametric model and an efficient calculation method, based on stochastic-reduced-order models, for fragility surfaces are proposed. 相似文献
17.
Generation of hazard-consistent fragility curves 总被引：1，自引：0，他引：1
This paper presents an analytical method for generating fragility curves of structures. In the proposed method, seismic sources, path attenuation, local soil conditions, and nonlinear building behavior are systematically considered. The uncertainties in the earthquake-site-structure system are quantified by considering the uncertainties in the seismic, site, and structural parameters that define the system. For an illustration, the proposed method is used to generate fragility curves and a damge probability matrix for Smith Hall on the main campus of The University of Memphis, Memphis, Tennessee. 相似文献
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19.
Fragility curves constitute an emerging tool for the seismic risk assessment of all constructions at risk. They describe the probability of a structure being damaged beyond a specific damage state for various levels of ground shaking. They are usually represented as two-parameter (median and log-standard deviation) cumulative lognormal distributions. In this paper a numerical approach is proposed for the construction of fragility curves for geotechnical constructions. The methodology is applied to cantilever bridge abutments on surface foundation often used in road and railway networks. The response of the abutment to increasing levels of seismic intensity is evaluated using a 2D nonlinear FE model, with an elasto-plastic criterion to simulate the soil behavior. A calibration procedure is followed in order to account for the dependency of both the stiffness and the damping on the soil strain level. The effect of soil conditions and ground motion characteristics on the global soil and structural response is taken into account considering different typical soil profiles and seismic input motions. The objective is to assess the vulnerability of the road network as regards the performance of the bridge abutments; therefore, the level of damage, is described in terms of the range of settlement that is observed on the backfill. The effect of backfill material to the overall response of the abutment wall is also examined. The fragility curves are estimated based on the evolution of damage with increasing earthquake intensity. The proposed approach allows the evaluation of new fragility curves considering the distinctive features of the structure geometry, the input motion and the soil properties as well as the associated uncertainties. The proposed fragility curves are verified based on observed damage during the 2007 Niigata-Chuetsu Oki earthquake. 相似文献