Effects of basin edge on the distribution of damage in 1995 Dinar, Turkey earthquake

An earthquake of magnitude M_L=5.9 occurred in Dinar, a town located at the edge of an alluvial basin in Southeast Anatolia, Turkey. Inflicted structural damage throughout the town was highly concentrated in a region located on the alluvium and adjacent to the rock outcrop bounding the eastern side of the town. As an attempt to explain this discrepancy, possible effects of the edge of basin on which the town is located were investigated through 1D and 2D response analyses. Response spectra, computed at distinct locations of the town were contrasted to the building damage statistics of the three zones identified in the town. It is found that the 1D analyses considerably underpredict the spectral response in the heavily damaged area. Differences between the spectral responses obtained from the two approaches diminish with increasing distance from the rock outcrop. These results, which indicate that the 2D amplification was significant over a distance from the edge of the basin, provide a meaningful explanation for the observed distribution of damage throughout the town.     

汶川县威州镇砖混结构房屋抗震加固设计

针对在5.12汶川大地震中,汶川县城所在地-威州镇遭受中等破坏的砖混结构房屋,通过某工程实例,给出了该类房屋具体的加固设计和施工方法,加固前绝大数楼层的综合抗震能力指数小于1,加固后所有楼层的综合抗震能力指数大于1。最后提出了一些建议,为类似工程提供一些参考。     

地震遗址加固方法的探讨

2008年汶川特大地震和2010年玉树大地震将许多县城夷为平地。为纪念这特定的历史事件,一些受地震破坏的建筑物和文物建筑遗址被定位为地震遗址,需对其进行抢险加固。本文以北川老县城K06商住楼和玉树县格萨尔宾馆为例,介绍了地震遗址的破坏情况,分析了破坏的原因,初步探讨了地震遗址的加固方法。     

节能住宅地震反应分析

为研究节能房屋的抗震能力,本文基于墙体试验研究成果,建立了墙体的恢复力模型及其抗震抗剪强度公式,并对内砖外加气混凝土砌块墙体节能房屋进行了地震反应分析.本项研究为节能住宅的推广应用提供了抗震设计依据.     

Effects of surface topography on seismic ground response in the Egion (Greece) 15 June 1995 earthquake

The Greek coastal town of Egion on 15 June 1995 was shaken by a strong, small epicentral distance, earthquake that caused heavy damages to buildings and loss of life. The damages were concentrated in the central elevated part of the town whereas the flat coastal region remained almost intact. This non-uniform distribution of damage is studied in this article in terms of surface topography effects by conducting seismic response analyses of a simplified 2-D profile of the town. A dynamic finite element code implementing the equivalent-linear soil behavior (FLUSHPLUS) was used for the analyses and it was found that the step-like topography amplified greatly the intensity of motion without affecting its frequency content. The analyses showed that the motion recorded by an accelerograph installed at the center of the town is in agreement with the computed values; they also indicated a particularly intense amplification close to the crest of the steep slope, where a multi-story RC residential building partially collapsed. In contrast, the level of motion was found to be low at the flat coastal zone of the town where the earthquake damages were insignificant. It is concluded that the characteristic surface topography of the town played an important role in modifying the intensity of base motion.     

多层空心砌块房屋混凝土结构抗震性测试研究

为了研究多层空心砌块房屋混凝土结构抗震性测试,按照1∶5缩尺比例建造空心砌块房屋混凝土结构模型进行抗震性测试实验。根据实际原型参数遵从相似理论的要求选择模型参数,通过电液伺服加载装置和液压千斤顶加载水平、垂直方向荷载,对所建造模型进行动力特性测试、地震反应分析、结构最大地震反应以及位移响应进行了实例分析。结果表明,随着破坏程度加大,模型结构自振频率随之减小,阻尼比随之增大;有芯柱多层空心砌块房屋模型的抗震效果较强;强震状态下,结构动力特性变化较大,破坏层聚集了房屋结构的最大反应;当加速度为125 cm/s时,结构最大位移为2.73 mm,低于规范值,模型结构具备一定延性。     

非正规设计框架结构抗震加固支撑效果对比研究

近年来,随着经济、技术的进步以及抗震意识的加强,建筑结构加固也飞速发展。在地震多发的农村地区,为了提高建筑结构的抗震性能,但同时又缺乏一定的经济基础和理论知识支撑,导致很多简单粗糙的支撑建筑结构的措施出现,这些支撑方案大多缺乏科学的设计与评估。本文针对这一现象,以某典型的非正规设计的3层2跨框架结构为例,分析评价支撑边框和支撑中框对该框架结构地震作用下抗倒塌性能的影响。通过增量动力分析（IDA）计算方法,结合结构易损性方程评估结构的抗倒塌能力,计算结果表明支撑中框和支撑边框能够将非正规结构在罕遇地震作用下的倒塌概率从17.5%降至2.4%和6%。在此基础上,进一步分析了2种支撑位置对结构在3个典型地震强度作用下对结构响应的影响。结果表明,支撑框架结构中框对结构抗倒塌能力的提升和抗震性能的保证效果比支撑边框更好,在条件允许的情况下,应优先考虑支撑中框。     

An alternative approach for the seismic rehabilitation of existing RC buildings using seismic isolation

Usually, buildings with seismic isolation are designed to comply with an operational building performance level after strong earthquakes. This approach, however, may limit the use of seismic isolation for the seismic rehabilitation of existing buildings with low lateral strength or substandard details, because it often requires invasive strengthening measures in the superstructure or the use of expensive custom‐made devices. In this paper, an alternative approach for the seismic rehabilitation of existing buildings with seismic isolation, based on the acceptance of limited plastic deformations in the superstructure under strong earthquakes, is proposed and then applied to a real case study, represented by a four‐storey RC frame building. Nonlinear response‐time histories analyses of an accurate model of the case‐study building are carried out to evaluate the seismic performances of the structure, comparing different rehabilitation strategies with and without seismic isolation. Initial costs of the intervention and possible (future) repair costs are then estimated. Based on the results of this study, values of the behavior factor (i.e. response modification factor) higher than those adopted in the current codes for base‐isolated buildings are tentatively proposed. Copyright © 2015 John Wiley & Sons, Ltd.     

基于GIS的城市建筑群动力响应分析模型建模方法研究

建筑群震害响应模拟是现代城市震害防御管理工作的基础。高效的建筑信息获取方法与科学合理的建筑群动力响应分析模型建模方法是快速、准确震害模拟的前提,也是震害防御科学管理、迅速决策和精准施策的必要保障。本文提出利用GIS平台进行矢量地图数据采集、多图层空间叠加分析及地形分析;结合我国各地市政府数据开放平台,获取建筑使用功能、建成年代、结构类型及场地类别等基本信息;在此基础上建立一套基于真实城市信息的建筑群动力响应分析模型建模方法。该方法操作简便、模型精度高并且建模速度快,可实现城市区域大规模建筑群高效建模。针对成都市某街区建筑群进行数据采集和模型建立,验证了该方法的可行性和有效性。     

Post-earthquake building damage assessment in Yushu using airborne SAR imagery

The synthetic aperture radar (SAR) plays an important role in earthquake emergency response because of its all-time and all-weather imaging capabilities. On April 14, 2010, an MS7.1 earthquake occurred in Yushu county, Qinghai province of China, causing a lot of buildings collapsed. In this paper, the building damage in Yushu city due to the earthquake was assessed quantitatively using high-resolution X-band airborne SAR image. The features of the buildings with different damage levels (collapsed, partial collapsed, non-collapsed) in the SAR image were analyzed first. Based on these building features, we interpreted the individual building damage in Yushu city block by block and got the numbers of the collapsed, partial collapsed and non-collapsed buildings separately for each block, referring to pre-earthquake QuickBird image when necessary. Let the damage index of individual collapsed, partial collapsed, non-collapsed building be 1, 0.5, 0 respectively, the remote sensing damage index of each block was then calculated through remote sensing damage index equation. Finally, the preliminary quantitative relationship between the remote sensing damage index interpreted from the SAR image and that interpreted from the optical image was built up. It can be concluded that a desirable damage assessment result can be derived from high-resolution airborne SAR imagery.     

Damage to residential buildings in Hveragerði during the 2008 Ölfus Earthquake: simulated and surveyed results

This study analyses the performance of residential buildings in the town of Hveragerði in South Iceland during the 29 May 2008 Mw 6.3 Ölfus Earthquake. The earthquake occurred very close to the town, approximately 3–4 km from it. Ground shaking caused by the earthquake was recorded by a dense strong-motion array in the town. The array provided high-quality three-component ground acceleration data which is used to quantify a hazard scenario. In addition, surveys conducted in the town in the aftermath of the earthquake have provided information on macroseismic intensity at various locations in the town. Detailed information regarding the building stock in the town is collected, and their seismic vulnerability models are created by using building damage data obtained from the June 2000 South Iceland earthquakes. Damage to buildings are then simulated by using the scenario hazard and vulnerability models. Damage estimates were also obtained by conducting a survey. Simulated damage based on the scenario macroseismic intensity is found to be similar to damage estimated from survey data. The buildings performed very well during the earthquake—damage suffered was only 5 % of the insured value on the average. Correlation between actual damage and recorded ground-motion parameters is found to be statistically insignificant. No significant correlation of damage was observed, even with macroseismic intensity. Whereas significant correlation was observed between peak ground velocity and macroseismic intensity, neither of them appear to be good indicators of damage to buildings in the study area. This lack of correlation is partly due to good seismic capacity of buildings and partly due to the ordinal nature of macroseismic intensity scale. Consistent with experience from many past earthquakes, the survey results indicate that seismic risk in South Iceland is not so much due to collapse of buildings but rather due to damage to non-structural components and building contents.     

基于三维图像模式识别的西藏东南部地震灾害损失风险评估

本文在对西藏东南部各县的建筑类型、数量、易损性调查的基础上,对不同类型的建筑建立了模式类向量,使用三维图像模式识别技术估计了各类型建筑在西藏东南部各县市的数量分布,建立了不同建筑物的结构易损性和人口易损性模型,并且估算了西藏东南部各县在遭遇一次设定地震时的损失分布和基于危险性的未来50年可能的损失分布情况.本文研究表明,若曲松—桑日发生7.5级地震,可能造成拉萨、山南两市较重的人员伤亡,其中曲松县和乃东区伤亡最重.西藏东南部未来50年建筑地震风险最高的地区是拉萨市区、林芝市区和错那县,其中拉萨市区的建筑财产损失风险最高.     

汶川大地震汉源县城建筑物震害调查

汶川地震中,距离震中约200公里的汉源县出现了明显烈度异常现象,汉源县城建筑物震害表现尤为明显.为了解释这一现象,在汶川大地震第一阶段科学考察中,相关调查小组对汉源县城建筑物震害开展了相应的调查.调查结果表明,该处烈度异常现象确实存在,烈度异常与该处局部场地条件有一定的联系.     

西藏米林MS6.9地震震害分析

2017年11月18日,西藏自治区林芝市米林县发生M_S6.9地震。本文以2017年9月中下旬中国地震局地球物理研究所西藏野外考察建筑资料为基础,分析林芝周边4个考察点的房屋建筑抗震性能以及震后房屋建筑和震区道路的震害情况。重点分析鲁朗扎西岗村、易贡堰塞湖堤、米林镇帮加村、波密县岗堆镇岗堆村等4个考察点的房屋建筑情况以及震后破坏情况。这几个考察点分别位于地震烈度的Ⅶ度区和Ⅵ度区外。并给出震区房屋建筑在未来抗震设防的意见。      

Damage seismic scenarios for Angra do Heroísmo, Azores (Portugal)

Angra do Heroísmo, located in Terceira Island, is the main town of the Central Group of Azores Archipelago and it is classified as World Heritage by Unesco. The preservation of this patrimony, located inside a seismic region, includes the implementation of a policy to protect it against earthquakes. The development of credible damage scenarios could help this objective, as they can be used in prevention measures to minimize the impact of future earthquakes. Two methods were used for seismic damage estimation: the capacity spectrum method and a new method, based on the direct response of a 1D non-linear oscillator to simulate the building seismic performance. Both methods seem to overestimate the damages for the near sources, but this could be due to the empirical model used to estimate the input ground motion. Comparison with the damage observed after the January 1st, 1980 earthquake show a large discrepancy with an underestimation bias, which can be explained, mainly, by the difference of building performance and on the plausible hypothesis of 2D site effects.     

建筑结构的屈曲约束支撑对其抗震加固性能的影响

当前方法采用伸臂桁架加固建筑结构时,未考虑建筑结构的屈曲约束支撑力的影响,伸臂桁架与建筑结构的连接不牢固,导致其对建筑结构的抗震加固性能较差。故此,深入分析建筑结构的屈曲约束支撑对其抗震加固性能的影响,设计建筑结构抗震加固方案,利用高强螺栓节点经由连接钢板实现屈曲约束支撑与建筑结构的铰接固定。分别从支撑变形同建筑结构层间位移的关系、建筑结构支撑承载力、多遇地震影响下屈曲约束支撑框架的位移验算,以及罕遇地震影响下屈曲约束支撑的弹塑性位移验算方面,分析屈曲约束支撑对建筑结构抗震加固性能影响。经实验分析得出,建筑结构加入屈曲约束支撑后第一扭转周期同第一平动周期的比值降低0.14,X、Y两个方向的砌体墙同建筑结构的刚度比值降低6.9、8.0,最大顶点位移值降低15.4 mm、29.3 mm,抗震加固性能大大提高。     

Response of rigid body assemblies to dynamic excitation

Shaking table tests were conducted to investigate the response of rectangular wooden blocks and block assemblies of various sizes and slenderness to harmonic and earthquake base excitation. The shaking tests were followed by an analytical and a numerical study of response of single blocks and block assemblies. The analytical study was aimed at establishing criteria for the initiation of rocking and of overturning in response to harmonic base motion and consisted of solving numerically the differential equations of motion of a rigid block on a rigid foundation. The numerical study, in the course of which the response of both single blocks and block assemblies was examined, was implemented by means of the Distinct Element Method (DEM). Prior to the DE simulation of actual shaking tests, preliminary analyses were conducted to confirm numerical stability and to evaluate material and damping parameters. Comparing the recorded time histories with those given by the analytical study and the DE simulation, good agreement was found. The distinct element model in use appeared to follow the highly non-linear motion of rigid body assemblies faithfully to reality. On the basis of the results, provided that the necessary parameters are carefully estimated, the employed DE model can be regarded as an appropriate tool to simulate response of rigid body assemblies to dynamic base excitation.