Seismic Risk Assessment of Buildings in the Extended Urban Region of Athens and Comparison with the Repair Cost

A complete research of seismic risk assessment is presented herein focused on the existing build- ings of the extended urban region of Athens in Greece. The seismic risk assessment is fulfilled by discriminating the current study in two approaches, probable and actual, conducting afterwards between them a comparison analysis. In the first part, a pilot methodology is developed for the seismic loss assessment in monetary terms regarding the buildings damages, consistent with the National Programme for Earthquake Management of Existing Buildings (NPEMEB). The building stock consists of typical building types of Southern Europe and refers to 750,085 buildings (18.80% of buildings in Greece) situated in the entire region of Athens according to the results of the 2000-1 statistical census. A wider research of seismic risk assessment could include direct losses of infrastructures and indirect economic losses. The evaluation of loss due to building damage in a certain region requires an assessment of both seismic hazard and vulnerability of the building stock in the study area. Four different existing damage scenarios are applied for the vulnerability assessment. The results of the seismic risk assessment for the four different aspects of the es- timated damage and the different soil conditions are presented in a map of the study region. The existing vulnerability curves corresponding to defined types of buildings have been derived from the National Technical Chamber of Greece and also from recently developed DPMs. The last DPMs were obtained in a previous research (Eleftheriadou, 2009) from the process of a created damage database after the 7th of September 1999 Parnitha’s earthquake and comprised 180,945 buildings which developed damage of varying degree, type and extent. In the second part of the research, the seismic risk is evaluated from the available data regarding the mean statistical repair/ strengthening or replacement cost for the total number of damaged structures (180,427 buildings) after the same (1999 Parnitha’s) seismic event. Data regarding the compatible (budget approved according to the ministry’s provisions) repair cost has been collected. The structural losses in monetary terms for the 180,427 buildings damaged structures are evaluated equal to 2450.0 Μ€, 1887.8 Μ€ and 2118.9 Μ€ based on the previously mentioned statistical seismic risk data. The statistically derived repair cost for Attica is compared with the results of the economic loss esti- mation for buildings using the aforementioned risk assessment methodology. From the analysis results, the seismic scenario based on the recently developed DPMs (Eleftheriadou, 2009) pre- sented the better correlation (2627.77 M€) with the total statistically evaluated repair cost (2450.02 M€). It is important to stress that the inclusion of the coefficient parameter S overes- timates significantly the seismic losses. The last result should be taken into consideration in future risk researches. The comparison of the estimated economic loss with the statistical repair cost calibrates the reliability of the commonly used risk assessment method and serves in the im- provement of seismic security prioritizing the criteria for seismic rehabilitation programmes of existing buildings.

Mapping Seismic Vulnerability and Risk of Cities： The MASSIVE Project

MASSIVE （mapping seismic vulnerability and risk of cities） is a GIS-based earthquake preparedness system that was developed under the European Union Civil Protection Mechanism project （GA No. 070401/2009/540429/SUB/A4）, in order to provide civil protection authorities with accurate, and easily transferable tools for generating up-to-date maps of seismic hazard, seismic vulnerability and seismic risk of buildings, at the scale of the single building block. In addition, MASSIVE developed and ran state-of-the-art models to assess the risk for population evacuation in dense urban agglomerations given an earthquake event. The MASSIVE methodology was designed, implemented and validated considering two European pilot sites, heavily struck by recent earthquakes, which are the western part of the Larger Metropolitan Area of Athens （GR）, and the city of L＇ Aquila in the Abruzzo Region （IT）. The validation of the results using past earthquake records shows that the performance of MASSIVE is prosperous, achieving a correlation between the modeled and the on-site measured PGAs （peak ground accelerations） higher than 0.75, while the correlation between the on-site reported building damages and the ones predicted by the MASSIVE system has been of the order of 0.80.

Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings

Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings （CCSDB） has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model （PSDM）.The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.

甘肃积石山地震村镇典型建筑震害及成因分析

2023年12月18日甘肃省临夏回族自治州积石山发生6.2级地震,此次地震造成了大量的村镇建筑破坏和倒塌,并造成了多人伤亡,是典型的“小震大灾”。文中总结了积石山地震中震区村镇建筑典型震害特点和规律,并结合建筑的结构类型、建造年代和是否具有抗震构造措施进行了典型案例分析,总结此次地震震损较为严重的原因:部分自建房屋为砖柱和土坯墙,二者缺乏有效连接,自身抗震能力差,这点从同一院落具有圈梁构造柱的房屋基本完好而不具备抗震构造措施的房子破坏严重可以说明;部分房屋不同层存在开间变化导致竖向传力不连续;结构存在大量平面布置不规则的情况;结构局部不完整或存在薄弱部位;农村自建房屋,按照工匠习惯建设,未考虑地震作用下的受力要求,需要建立质量监管体制机制。

考虑场地液化的简支桥梁振动台试验研究

为了探究简支桥梁在可液化场地条件下的倒塌机理,结合实际震害调查,并对量大面广的简支桥梁进行了模拟液化场地下的振动台模型试验,采用持续增强的白噪声和正弦波作为激励,研究了简支桥梁在可液化场地条件下的倒塌机理。结果表明,振动台试验结果能够很好地再现液化现象,桩截面峰值应变位置随着液化的逐渐加深而下移,桩基自振频率随场地液化的逐渐加深而持续降低,而邻桩间距的不断增大会导致桥梁倒塌,试验结果与实际震害现象较为接近。研究对桥梁结构在地震作用下的土-结构相互作用具有一定的参考价值,也为现存类似桥梁的地震安全性评价积累了部分试验资料。

泸定6.8级地震典型震害调查与分析

对四川泸定6.8级地震极震区中磨西镇和得妥镇的建筑物进行震害调查与分析,发现具有“散、脆、偏”特性的建筑物破坏严重,而具备完好抗震构造措施的砌体结构、结构布置具备“匀”思想的建筑物震害较轻。基于“变形饱和”建筑物致灾机理和泸定地震震害调查结果,将建筑物常见的结构布置划分为5种典型形式:全硬脆轴线结构、全弱延轴线结构、全弱脆轴线结构、普通结构和具有“偏中带匀”特点的硬脆与弱延混搭结构,分析每种形式对应的震害表现及其内在机理。结果表明:全硬脆轴线结构、全弱延轴线结构和具有“偏中带匀”特点的硬脆与弱延混搭结构因未到达“变形饱和点”,震害表现极轻,几乎无可见裂缝,而其他2种结构布置形式的建筑均出现破坏,甚至倒塌。最后,结合“变形饱和”致灾机理对房屋抗震设计理念提出“匀”的建议。

接触爆炸作用下支撑式叠合结构抗震塌性能研究

常规武器作用下,地下构筑物主要在弹着点附近的局部区域发生破坏,并在迎爆面可能产生冲击或爆炸漏斗坑,同时在背爆面产生震塌漏斗坑,严重时则会产生贯穿破坏。提出了一种支撑式叠合结构,不同于在工业与民用建筑、水利水电工程、道桥及港口工程等领域中作为受力构件的叠合结构,支撑式叠合结构可以改变爆炸波的传播路径从而达到有效减少背爆面震塌破坏的目的。通过TNT装药爆炸试验和数值模拟研究,获取了支撑式叠合结构的抗震塌性能、破坏形态及爆炸波传播特征和传播路径,并与单层钢筋混凝土厚板的抗震塌性能进行对比分析。研究结果表明,同等药量作用下,相比于厚度相近的钢筋混凝土单层板,支撑式叠合结构的抗震塌破坏性能有显著提高。

Damage Investigation of the Hutubi Ms6.2 Earthquake on December 8,2016

The Hutubi M_S6.2 earthquake occurred on December 8, 2016, in Hutubi County,Xinjiang Uygur Autonomous Region, causing three people injured. The earthquake effected areas mainly included 25 townships and towns,plus Hutubi County and Manas County in Changji,Hutubi and Manas. The total effected area is 12,450 km^2. In this paper,we summarize the seismo-tectonic background and geomorphic features of the earthquake zone. Under the guidance of the standard "The Earthquake Site Works-Parts4: Assessment of Direct Loss",the damage to buildings and lifeline systems with various structural types are introduced,and we ultimately estimate the direct economic losses to mud-wood houses and the destruction of brick-wood houses. Our results indicate that"The Urban and Rural Seismic Safe Housing Project"played a key role in reducing this earthquake disaster.

考虑近断层强震影响的铁路站房结构地震易损性分析

由于铁路选线限制,部分铁路站房修建在高烈度区,且靠近地震断层。为保障铁路站房结构的抗震安全,以某站房结构为研究对象,分析考虑近断层强震影响的站房结构地震易损性。首先,分别采用近断层抗震设计谱和规范抗震设计谱对铁路站房结构进行抗震设计,建立相应的站房结构数值模型,并对模型进行验证;然后,选取24组近断层脉冲型地震动,分析铁路站房的地震响应,并分别定义站房结构中混凝土框架、钢屋架和砌体填充墙的损伤指标;最后,对2种设计谱设计的铁路站房局部及整体地震易损性进行评估。结果表明:在8度罕遇地震作用下,考虑近断层强震影响的站房结构相较于不考虑的,其混凝土框架和砌体填充墙出现毁坏的超越概率分别下降58.26%和19.82%,整体结构出现毁坏的超越概率上下界分别下降17.27%和19.83%;考虑近断层强震影响的抗震设计能够降低站房结构发生损伤的概率,提高其抗震性能;考虑近断层强震影响的站房结构损伤概率由大到小依次为砌体填充墙、混凝土框架、钢屋架。基于此,地震断层附近的铁路站房结构抗震设计应考虑近断层强震的影响,并加强砌体填充墙的抗震构造措施。

房屋建筑经验性地震易损性曲线研究进展

基于历史地震的海量震害数据建立经验性地震易损性曲线是我国防震减灾工作的重要内容。结合相当数量的文献,系统梳理了国内外经验性地震易损性曲线的研究进展及有关的规范或标准,剖析了经验性地震易损性曲线建立过程中房屋建筑分类、破坏等级划分、地震动参数选择、曲线拟合等各个环节存在的不足,结合现代灾害调查手段,提出了优化和扩大震害数据、合理选择地震动参数、标准化经验性地震易损性曲线的建立流程等建议。

CFRP及钢板复合加固震损方钢管混凝土框架结构抗整体性倒塌能力分析

为了研究CFRP及钢板复合加固震损方钢管混凝土框架结构的抗整体性倒塌能力,基于OpenSees开放平台,通过折减材料的刚度和强度模拟地震损伤,建立3榀分别为未加固、中度损伤加固和重度损伤加固的两跨三层方钢管混凝土框架结构数值模型,对其进行低周往复分析,并通过与试验结果对比验证了模型的可行性。对震损加固前后的结构数值模型进行增量动力分析,绘制出结构倒塌破坏阶段的易损性曲线,通过计算结构抗倒塌安全储备系数来评估其抗整体性倒塌能力。结果表明,未加固构件、中度损伤加固构件和重度损伤加固构件的抗倒塌安全储备系数分别为1.8、2.18、2.07,中度损伤加固构件和重度损伤加固构件的抗整体性倒塌能力较未加固构件分别恢复并得到提升21.1%和15.0%,且满足“大震不倒”要求。因此,CFRP及钢板复合加固可以有效恢复并提高震损方钢管混凝土框架结构的抗整体性倒塌能力。

马尔康M_(S)6.0震群地震烈度分布与房屋震害特征分析

通过对2022年6月10日马尔康M_(S)6.0地震震群灾区实地调查,确定了此次地震的烈度分布,灾区最高烈度为Ⅷ度,灾区面积5719 km^(2)。灾区内调查的77个房屋建筑点主要为藏式石木结构、砖混结构、钢筋混凝土框架结构。对各烈度区内不同结构类型房屋的震害现象进行了整理,分析了不同结构类型房屋的抗震能力与震害原因。结果显示:①藏式石木结构房屋占比最大且破坏最严重,该结构房屋建造材料、工艺较差,在高烈度区房屋震害主要表现为倒塌或局部垮塌现象;②砖混结构房屋抗震性能较好,在高烈度区房屋震害主要表现为“X”型剪切或贯穿性裂缝,破坏严重的房屋多是无圈梁和构造柱的未设防砖混结构;③钢筋混凝土框架结构房屋抗震性能较好,在此次地震中主体结构完好,但在高烈度区房屋震害主要表现为填充墙明显裂缝和装饰层脱落。

基于IDA方法的地铁车辆基地TOD开发全框支剪力墙结构抗震性能评估

全框支剪力墙结构因上部塔楼剪力墙完全不落地而存在竖向构件不连续、刚度突变、大底盘多塔等不规则项,为综合有效评估此种超限结构的抗震性能,基于增量动力分析(IDA)方法得到不同地震烈度下结构最大层间位移角分布情况,并将结构性能水准划分5个等级,最终分析其地震易损性和损伤风险性。研究结果表明,结构随地震动峰值加速度(PGA)增大逐渐屈服并最终倒塌,不同地震记录时结构IDA曲线具有明显离散性;结构在7度多遇地震作用下处于正常使用性能水准的概率为97.914%,罕遇地震作用下结构倒塌的概率仅为0.053%;生命安全和接近倒塌性能水准对应的PGA中位数分别为1.287g和1.411g,远高于预估罕遇地震PGA;结构正常使用、基本可用、修复可用和接近倒塌性能水准50年超越概率分别为4.89%、1.74%、0.112%和0.046%。综上所述,结构满足预设抗震性能目标,具有良好的抗震性能及抗倒塌能力。

悬顶采空区下煤层开采压架危险性评估及勘探技术

榆林市某矿房柱式悬顶采空区综采过程中,出现了多次压架事故,为了减少压架事故发生,保障煤矿安全生产,从该矿压架机理分析入手,进行了压架危险性评价,提出应力集中区勘探技术方案,为卸压防治提前打下基础。结果表明:工作面出煤柱开采安全的煤层间距临界条件为D0≥67.46 m,该矿5-2煤和5-3煤间距远远小于临界条件,开采5-3煤过程中存在压架风险;5-2煤层房采悬顶采空区下部5-3煤长壁支架富余系数为19%,压架危险性评价为为危险;采用地震波CT法对悬顶采空区导致的应力集中区进行探测设计,设计道间距为6 m,炮间距为3 m,每次探测覆盖范围为沿工作面长度为66 m,达到工作面超前卸压范围要求,每次12道检波器合计66 m循环探测,直到工作面探测卸压完成。

贵州西部地区农村民居抗震性能及震害分析——以威宁县为例

贵州位于南北地震带南端,近年来发震的频度和强度均处于我国平均水准之上。为了解贵州西部地区农村民居的抗震性能及震害情况,本文以地震密度和强度均较大的威宁县为例,通过实地调研,深入研究该地区农村民居抗震设防问题,分析总结该地区农村民居主要结构类型的抗震能力及遭受地震时可能发生的震害情况,并提出如何加强农村民居抗震设防的建议。

基于事故树的观测山洞施工风险分析

隧道施工是丽江地震台迁建项目的重要环节,而隧道施工常存在塌方风险。应用鱼刺图对隧道施工风险进行识别,确定塌方为该项目施工主要风险,在此基础上采用事故树分析法对塌方风险进行定性、定量分析。对比分析不同影响因素的结构重要度,发现在项目施工过程中项目管理人员和施工人员所导致的人为因素是引发塌方风险的重要原因。因此健全管理模式,加强人员安全意识培训,制定合理的应急预案尤为重要。

汶川地震重灾区典型钢筋混凝土框架结构震害现象

介绍了5·12四川汶川地震近震源区钢筋混凝土框架结构的震害现象,从房屋整体跨塌、房屋整体严重歪斜、房屋部分集中垮塌、房屋部分楼层垮塌、房屋底层侧移过大等方面总结了震害现象,从剪切、剪压、压屈、压弯、塑性铰等破坏方面分析了梁柱震害现象.从结构平立面布置、结构体系和结构构件等方面初步分析了钢筋混土框架结构破坏的主要原因.

2014年云南鲁甸地震和景谷地震的震害对比研究

2014年8月3日云南鲁甸发生MS6.5地震,10月7日云南景谷发生MS6.6地震。这2次地震的震级、地震类型、震源深度等相差不大,但地震所造成的人员伤亡、房屋建筑损毁程度、地震地质灾害等却相差很大。在地震现场调查资料的基础上,对比分析地震造成的崩塌、滑坡、地裂缝、砂土液化、房屋建筑损毁等灾害轻重差别的主要原因。研究表明,鲁甸地震灾区地质构造复杂,地层破碎,人口密度大,房屋建筑抗震性能差;而景谷地震灾区地质环境较好,植被茂密,人口密度低,相比同量级地震的加速度小,房屋建筑结构抗震性能较好。总体而言,鲁甸MS6.5地震的震害比景谷MS6.6地震要严重得多。

地震人员伤亡估算方法研究

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