考虑震害因子耦合作用的砌体建筑群破坏概率模型研究

砌体建筑群在地震中往往破坏严重损失巨大,合理评估地震作用对不同种类砌体结构造成破坏的风险变得至关重要。传统基于后验概率的地震危险性分析方法忽略了砌体建筑个体差异性的影响,未深入考虑多种震害因子的耦合作用。本文以华南地区砌体建筑群为例,开发了一种集成概率方法来对城市砌体结构的破坏风险进行建模,考虑建筑年代、层数、使用用途和墙厚四类震害因子的耦合影响,采用(Kolmogorov-Smirnov)K-S检验,在设定地震动参数下选取Gaussian分布、Log-Normal分布、Gumbel分布和Beta分布四种概率分布对该地区砌体建筑物的破坏状态概率分布参数进行拟合。通过均方根误差(Root Mean Square Error)RMSE进行拟合优度评价,最终建立基于Gaussian分布和Log-Normal分布的砌体建筑物破坏联合概率模型。最后,以华南地区三个城市典型砌体建筑物为例进行实例对比验证,将基于本文建立的建筑破坏概率模型推算出的砌体建筑群震害矩阵与基于单体结构分析得到的震害矩阵进行对比,与理论值最大偏差为0.033 3。研究表明：本文构建的集成概率方法能够获得更加合理的城市砌体建筑...     

Seismic fragility assessment of low-rise stone masonry buildings

Many historic buildings in old urban centers in Eastern Canada are made of stone masonry reputed to be highly vulnerable to seismic loads.Seismic risk assessment of stone masonry buildings is therefore the first step in the risk mitigation process to provide adequate planning for retrofit and preservation of historical urban centers.This paper focuses on development of analytical displacement-based fragility curves reflecting the characteristics of existing stone masonry buildings in Eastern Canada.The old historic center of Quebec City has been selected as a typical study area.The standard fragility analysis combines the inelastic spectral displacement,a structure-dependent earthquake intensity measure,and the building damage state correlated to the induced building displacement.The proposed procedure consists of a three-step development process:(1) mechanics-based capacity model,(2) displacement-based damage model and(3) seismic demand model.The damage estimation for a uniform hazard scenario of 2% in 50 years probability of exceedance indicates that slight to moderate damage is the most probable damage experienced by these stone masonry buildings.Comparison is also made with fragility curves implicit in the seismic risk assessment tools Hazus and ELER.Hazus shows the highest probability of the occurrence of no to slight damage,whereas the highest probability of extensive and complete damage is predicted with ELER.This comparison shows the importance of the development of fragility curves specific to the generic construction characteristics in the study area and emphasizes the need for critical use of regional risk assessment tools and generated results.     

Experimental investigation of seismic behaviour of the ancient Protiron monument model

Throughout history, dry-stone masonry structures have been strengthened with different types of metal connectors in order to increase their resistance which enabled their survival, especially in the seismically active area. One such example is the ancient Protiron monument placed in the Peristyle square of the Diocletian's Palace in Split, Croatia. The Protiron was built at the turn of the 3rd century as a stone masonry structure with dowels embedded between its base, columns, capitals and broad gable. The stone blocks in the broad gable were connected by metal clamps during restoration at the beginning of the 20th century. In order to study the seismic performance of the strengthened stone masonry structures, an experimental investigation of seismic behaviour of a physical model of the Protiron was performed on the shaking table. The model was designed as a true replica model in a length scale of 1:4 and exposed to representative earthquake with increasing intensities up to collapse. The tests provided a clear insight into system behaviour, damage mechanism and failure under intensive seismic load, especially into the efficiency of connecting elements, which had a special role in increasing seismic resistance and protection of the structure from collapse. Additionally, this experiment provided valuable data for verification and calibration of numerical models for strengthened stone masonry structures.     

村镇建筑砌体结构的动力特性分析

为探讨村镇建筑中低层砌体结构的动力特性与振动机理,基于农居调查实测的布置及材料性能数据,在ABAQUS软件中建立考虑结构布置、材料强度及有限元网格控制等参数的7个有限元模型方案,对各模型进行结构动力特性分析,并对比分析其振动形态、振型分量及振型周期。分析表明,村镇建筑中按常规布置的砌体结构,其振动特性不利于结构抗震;砌体材料性能劣化在降低结构承载能力的同时还会放大高阶面外振动分量的地震作用,加剧承重墙在地震中发生外闪倒塌的机率;如采取措施实现结构的基本振型为沿横向平动,则其振动特性表明横墙的承重与抗侧能力均可有效发挥,且面外振动的高阶振型被抑制,提高了结构抗震能力;此外,本文还提出ABAQUS对壳单元沿厚度方向的网格控制要求。     

基于BIM的建筑砌体结构抗震性能评估方法研究

建筑砌体结构抗震性能评估,对建筑结构安全的稳定性至关重要。本文从四个方面分析建筑砌体结构抗震性能提升的条件,根据建筑结构的抗震性影响因素,评估抗震能力。构建建筑砌体结构抗震性能的评估BIM指标体系;利用BIM模型中的三角模糊数,定量计算建筑砌体结构抗震性能指标的模糊判断矩阵,得到建筑砌体结构的三角模糊数值,分析筑砌体结构抗震性能指标的单排序情况,结合对建筑砌体结构抗震性能评估体系指标权重系数和单项得分的计算,实现基于BIM的建筑砌体结构抗震性能评估。结合模拟建筑实例分析,利用建筑结构倒塌概率测试建筑砌体结构的抗震性能,并利用评估结果与实际评估结果的拟合度测试提出方法的准确性。实例结果证明,能够准确的得到抗震性能的评估结果。     

增设翼柱的底商多层砌体房屋抗震性能试验研究

为研究在结构前纵墙底层部位增设翼柱对底商多层砌体房屋抗倒塌性能的影响,分别设计了一个1/5缩尺比例的普通底商多层砌体房屋及增设翼柱的砌体房屋模型分别进行振动台试验研究,对比分析各模型的破坏过程、加速度放大系数、相对位移及典型位置应变等参数。结果表明,在同样的地震动输入下,带有翼柱的底商多层砌体房屋破坏程度、层间相对位移及层间位移角均明显低于普通底商多层砌体房屋,带有翼柱的底商多层砌体房屋抗倒塌性能显著提高。     

Adapting earthquake actions in Eurocode 8 for performance‐based seismic design

Performance‐based seismic design (PBSD) can be considered as the coupling of expected levels of ground motion with desired levels of structural performance, with the objective of achieving greater control over earthquake‐induced losses. Eurocode 8 (EC8) already envisages two design levels of motion, for no collapse and damage limitation performance targets, anchored to recommended return periods of 475 and 95 years, respectively. For PBSD the earthquake actions need to be presented in ways that are appropriate to the estimation of inelastic displacements, since these provide an effective control on damage at different limit states. The adequacy of current earthquake actions in EC8 are reviewed from this perspective and areas requiring additional development are identified. The implications of these representations of the seismic loads, in terms of mapping and zonation, are discussed. The current practice of defining the loading levels on the basis of the pre‐selected return periods is challenged, and ideas are discussed for calibrating the loading‐performance levels for design on the basis of quantitative earthquake loss estimation. Copyright © 2005 John Wiley & Sons, Ltd.     

基于ECC的小雁塔抗震加固性能分析

高延性纤维增强水泥基复合材料(ECC)是一种高强度、高延性的新型建筑材料,在加固工程中具有广泛的应用前景。本文利用ECC的高延性和抗剪性,提出一种采用ECC面层加固小雁塔的保护方案,以提高古塔抗震性能;通过有限元软件ANSYS进行模拟分析,比较了小雁塔加固前后的地震响应。分析结果表明:采用ECC面层加固可显著增强塔身整体的延性和承载力,有效地提高塔体损伤容限,为ECC在古塔抗震加固的实际应用中提供借鉴,可作为古塔抗震保护的新途径。     

Loss estimation for non‐ductile reinforced concrete building in Victoria,British Columbia,Canada: effects of mega‐thrust Mw9‐class subduction earthquakes and aftershocks

This paper presents, within the performance‐based earthquake engineering framework, a comprehensive probabilistic seismic loss estimation method that accounts for main sources of uncertainty related to hazard, vulnerability, and loss. The loss assessment rigorously integrates multiple engineering demand parameters (maximum and residual inter‐story drift ratio and peak floor acceleration) with consideration of mainshock–aftershock sequences. A 4‐story non‐ductile reinforced concrete building located in Victoria, British Colombia, Canada, is considered as a case study. For 100 mainshock and mainshock–aftershock earthquake records, incremental dynamic analysis is performed, and the three engineering demand parameters are fitted with a probability distribution and corresponding dependence computed. Finally, with consideration of different demolition limit states, loss assessment is performed. From the results, it can be shown that when seismic vulnerability models are integrated with seismic hazard, the aftershock effects are relatively minor in terms of overall seismic loss (1–4% increase). Moreover, demolition limit state parameters, uncertainties of collapse fragility, and non‐collapse seismic demand prediction models have showed significant contribution to the loss assessment. The seismic loss curves for the reference case and for cases with the varied parameters can differ by as large as about 150%. Copyright © 2015 John Wiley & Sons, Ltd.     

海南农村民居抗震性能调查与研究

海南农村民居以砌体结构为主,具有门窗开口大、层高较高和整体性强等特点.为了研究分析这类民居的抗震性能与抗震对策,在收集大量当地农村民居样本的基础上,综合出典型结构模型,并对该典型模型及基于该模型的隔震模型和加强结构模型分别进行了模拟地震振动台试验.试验结果表明:隔震技术能明显降低结构地震反应,在高烈度地区应适当推广和运用.原结构模型基本满足7.5度设防标准.在8度大震作用下,结构遭遇严重破坏但未倒塌,说明其具有一定的抗倒塌能力.结构加固后,整体抗震性能得到了加强.结合试验结果,给出了相应对策与建议.     

Effect of masonry infills on seismic performance of a 3‐storey R/C frame with non‐seismic detailing

The objective of this study is to investigate the effect of masonry infills on the seismic performance of low‐rise reinforced concrete (RC) frames with non‐seismic detailing. For this purpose, a 2‐bay 3‐storey masonry‐infilled RC frame was selected and a 1 : 5 scale model was constructed according to the Korean practice of non‐seismic detailing and the similitude law. Then, a series of earthquake simulation tests and a pushover test were performed on this model. When the results of these tests are compared with those in the case of the bare frame, it can be recognized that the masonry infills contribute to the large increase in the stiffness and strength of the global structure whereas they also accompany the increase of earthquake inertia forces. The failure mode of the masonry‐infilled frame was that of shear failure due to the bed‐joint sliding of the masonry infills while that of the bare frame appeared to be the soft‐storey plastic mechanism at the first storey. However, it is judged that the masonry infills can be beneficial to the seismic performance of the structure since the amount of the increase in strength appears to be greater than that in the induced earthquake inertia forces while the deformation capacity of the global structure remains almost the same regardless of the presence of the masonry infills. Copyright © 2001 John Wiley & Sons, Ltd.     

Method of expected earthquake losses estimation based on the frequency of seismic site intensity

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单体建筑无筋砌体加固体系的抗震韧性研究

单体建筑无筋砌体结构的抗震韧性较差,在地震中容易发生严重破坏和倒塌。为此,以抗震韧性为参数指标,对单体无筋砌体结构进行加固并分析,研究其在地震作用下的抗震能力。以某实际工程作为研究对象,运用ANSYS软件建立单体建筑无筋砌体加固有限元模型,选取中国汶川地震波、日本阪神大地震波、美国克恩县地震波、中国台湾集集地震波及人工地震波作为地震动输入,利用韧性指数法和韧性等级法,从无筋砌体加固体系在震后的修复费用、修复时间及人员伤亡等方面进行分析,得到抗震韧性评估结果。研究表明：(1)在罕遇地震、设防地震和多遇地震的情况下,单体建筑无筋砌体结构的层间位移、层间剪应力、破坏程度均大于单体建筑无筋砌体加固体系;(2)在受到地震强弱因素影响下,无筋砌体结构的抗震韧性指数最高为0.877,而其加固体系的抗震韧性指数最低为0.908;(3)在经历不同地震波后,无筋砌体结构受到较大损害等级占比较高,人员伤亡较重,需要花费较长的时间和较多的费用完成灾后重建;而经过加固后的无筋砌体结构,加固体系受到较小损害等级占比较高,人员伤亡较轻,且能够用较短的时间和较少的费用完成灾后重建。     

江苏高邮、宝应MS4.9级地震现场震害调查与破坏原因研究

江苏高邮、宝应Ms4．9级地震在极震区造成了数10间农村民居不同程度和不同方式的破坏,出现人员伤亡。震后对地震灾害现场进行震害调查与破坏原因研究,典型的震害特征包括砖砌体、砖木和砖混结构房屋局部倾倒、墙体贯通开裂、房顶瓦片掀翻和烟囱倒塌等。农村民居遭到破坏的主要因素包括：选址不当、施工质量较差、砂浆强度不够、缺少圈梁和构造柱等。同时,分析了竖向地震作用和鞭梢效应等地震效应,讨论了砖砌体和砖混结构抗震设计的加固方法和改善抗震性能的构造措施等,为农村民居的抗震设防和减轻震害损失等提供参考。     

组合墙结构房屋抗震性能的振动台试验研究

通过三个组合墙模型房屋的振动台试验，分析了组合墙结构体系房屋的动力性能和抗震能力，比较了底一层和底两层框架组合墙房屋和普通组合墙房屋的抗震性能。结果表明，八层组合墙房屋的抗震能力远远超过设计能力，可用于八度地区，底框架组合墙房屋的抗震性能优于普通组合墙房屋，底两层框架组合墙房屋也优于底一层框架组合墙房屋。     

大开间小型混凝土砌块10层模型房屋抗震性能试验研究(Ⅰ)

我国抗震设计规范（GB50011－2001）规定在6、7、8度区，混凝土小砌块结构分别可以建七、六、五层。由于混凝土小砌块结构的最大优势在于10－20层（与混凝土框架或框架剪力墙结构比）。本文按1／4比例制作了10层混凝土小砌块结构模型，按7度设防要求实施构造措施，通过振动台试验研究模型结构的抗震性能。结果表明，模型结构完全能够满足在7度区“小震不坏，大震不倒”的要求。圈梁、构造柱以及水平拉结筋构成的约束体系抗震作用是明显的。试验利用砌块的非注芯孔灌注铁砂来模拟墙体出平面动力效应。在本模型的构造措施下，平出面反应不对结构破坏起控制作用。     

砌体结构在2008汶川大地震中的震害经验

本文首先列举了砌体结构在2008汶川大地震中的典型震害现象,通过这些现象分析了此次地震中砌体结构的震害特点,归纳了其震害规律和教训,总结了必须坚持的抗震原则及对今后砌体结构抗震设计的启示,同时,探讨了几个应该注意的重点抗震问题,提出了进一步加强砌体结构抗震性能的建议。文中指出,砌体结构只要坚持正确的抗震理念,加强构造措施,落实抗震规范的设计要求,保证施工质量,就能达到相应的抗震设防目标。     

从砌体的震害看抗震设计观念中存在的问题

以云南省破坏性地震中砌体结构房屋的典型震害实例,分析、总结了影响砌体结构抗震性能的措施和经验。针对按现行抗震规范设防后仍要遭受巨大经济损失这一事实,作试图从抗震设计规范的基本理念上分析引起破坏的原因,从而指出研究结构性能设计理论的必要性。     

强震作用下砌体结构倒塌过程仿真分析

四川汶川地震中大量砌体房屋倒塌,造成巨大人员伤亡。为研究和预防砌体结构震害,本文概述了多层砌体房屋的主要震害特点,研究了砌体结构地震倒塌分析方法、失效单元与结构倒塌等关键技术问题。利用动力有限元程序LS-DYNA模拟了砌体结构的倒塌过程。仿真计算的结果与真实倒塌过程吻合较好,说明通过合理选取计算参数和计算模型,可以对这种特殊的复杂破坏过程进行模拟分析和仿真。通过再现倒塌过程,发现了结构在强震作用下的薄弱环节,为提高砌体结构抗震性能研究、建立结构防倒塌机制提供了有力的技术支撑。     

Seismic capacity of irregular unreinforced masonry walls with openings

Masonry buildings are often characterized by geometric irregularities. In many cases, such buildings meet global regularity requirements provided by seismic codes, but they are composed by irregular walls with openings. The latter are masonry walls characterized by (i) openings of different sizes, (ii) openings misaligned in the horizontal and/or vertical direction, or (iii) a variable number of openings per story. An irregular layout of openings can induce not only a nonuniform distribution of gravity loads among masonry piers but also unfavorable damage localizations resulting in a premature collapse of the wall and hence a higher seismic vulnerability. This paper is aimed at providing a simplified methodology to assess the effects of irregularities on the in‐plane seismic capacity of unreinforced masonry (URM) walls with openings. To this end, a macroelement method was developed and validated through experimental results available in the literature. The proposed methodology was based on the quantification of wall irregularities by means of geometric indices and their effects on seismic capacity of URM walls with openings through both sensitivity and regression analyses. Sensitivity analysis was based on a high number of static pushover analyses and allowed to assess variations in key seismic capacity parameters. Regression analysis let to describe each capacity parameter under varying irregularity index, providing empirical models for seismic assessment of irregular URM walls with openings. The in‐plane seismic capacity was found to be significantly affected by wall irregularities, especially in the case of openings with different heights. Copyright © 2012 John Wiley & Sons, Ltd.