从集集地震看建筑物震害与地震动参数的关系

本文根据9．21台湾集集大地震中南投县、台中县、台北县和苗栗县的建筑物震害调查资料确定出这4个主要受害地区的平均震害指数,然后义计算出这4个地区的地震动峰值加速度、峰值速度、峰值谱加速度、峰值谱速度、峰值谱位移的平均值。将这些均值分别与平均震害指数进行基于最小二乘法的线性回归,发现峰值速度和震害指数有非常好的相关性,相关系数接近1．0,而峰值加速度与震害指数相关性只有0．8,这说明地震动峰值速度能够体现地震动对脆性结构的破坏势,与以往将不同次地震的记录和资料混淆在一起研究而获得峰值加速度与震害有很好相关性形成了对比。     

集集地震等震线和PGA、PGV等值线关系的研究

本文通过比较集集地震的等震线、加速度和速度等值线的相似度,发现加速度等值线和烈度等震线有更好的相似性,后通过数学分析也得到了相同的结果。由于集集地震中受损的大部分是短周期脆性结构,本文的研究结果可以说明:和峰值速度相比,地震动峰值加速度能够更好地体现地震动对脆性结构的破坏势。峰值速度也和震害有一定的相关性,但对于脆性结构它所体现的破坏能力不如峰值加速度。     

基于砌体结构破坏损伤的地震烈度物理标准研究

为了研究基于砌体结构破坏的地震烈度物理标准,将15个地震动参数按属性(峰值、频率、持时和能量)分成4类,将地震记录按地震动三要素(峰值、频率、持时)分成3组,求出每组记录作用下砌体结构的延性系数,计算出各个参数值和延性系数的相关系数,比较分析这些相关系数发现地震动峰值加速度、有效峰值加速度、地震动输入能量和滞回耗能都能表征地震动对砌体的破坏势,并且这4个参数都和烈度有很好的相关性,可以作为烈度的物理标准。     

地震烈度与地震动峰值的转换

本文以强震记录地面水平向平均峰值为基本数据,研究了在无条件、分别或同时考虑房屋层数和场地类别的前提下,地震烈度与地震动峰值的对应关系.并依据统计结果讨论了峰值均值随烈度的变化规律,给出了把烈度转换成地面峰速度、峰加速度或设计地震反应谱的建议方案.最后还讨论了把设计地震反应谱转换成地震烈度的方法,给出了建议的转换方案.      

中国西部地区利用烈度数据估计地震动参数的方法

通过最近收集到的中国西部地区的6次地震的地震动参数和烈度数据,建立了该地区适用于贝叶斯方法的各烈度档P(I|GM)的经验分布。利用2011年发生的四川炉霍地震和新疆伽师地震资料验证了依据烈度数据用贝叶斯方法估算峰值加速度的可行性。研究结果还表明,用贝叶斯方法估计的参数精度与选择的先验概率(衰减关系)显著相关。针对这2次地震,用各烈度档地震动参数的均值法、地震动衰减关系法及贝叶斯法3种方法估算的峰值加速度值与峰值加速度观测值之间的均方根比较表明,用贝叶斯方法估算的参数精度优于用另2种方法所获结果。     

Housner谱烈度的一种快速近似算法

Housner谱烈度及修正谱烈度作为基于加速度记录时程直接得到的地震动强度参数,与建筑结构破坏及地震宏观烈度存在较高的相关性,是可靠的地震仪器烈度物理参数指标。然而,相对于地面加速度峰值、地面速度峰值等地震动峰值参数,三分量加速度记录对应的谱烈度计算过程较为复杂,耗时相对较长,影响了利用谱烈度确定地震仪器烈度的时效性。基于对强震动加速度记录的统计分析,本文提出了谱烈度的快速近似算法,仅计算4个方向上的谱烈度值,采用其中3点作圆即可获得水平面内谱烈度迹线的近似最大值,使计算速度提高了45倍,且保持了谱烈度作为地震仪器烈度物理指标的精度。利用在汶川M_S 8.0地震等386次M_S > 3.0地震中获取的2701组强震动加速度记录,经可靠性检验,结果表明所提出的Housner谱烈度快速近似算法的计算误差在±4.5%以内,可以同时满足地震仪器烈度速报的可靠性和时效性需求。     

汶川地震烈度衰减异常——与郯城、海原地震的比较

在地震安全性评价以及地震区划等研究工作中,选用合适的地震动参数(加速度、速度等)衰减关系是非常重要的.由于缺少强震记录,我国目前的地震动参数衰减关系一般采用胡聿贤和张敏政(1984)提出的转换方法获得,通过利用既有烈度资料又有强震记录的地区(参考地区)的烈度衰减关系和地震动参数衰减关系,经过转换得到只有烈度资料的研究地区的地震动参数衰减关系.上述工作需要使用适合各地区的地震烈度衰减关系来体现不同地区的地震活动与震害分布的地域性特点.     

基于地震台网资料快速发布的震动烈度标准及其应用研究

在总结现有烈度计算方法的基础上,通过比较中国地震烈度评定表和台湾烈度评定表,提出以水平向地震动峰值加速度为标准的震动烈度表.表中采用1～10度共10级划分方式,每度都有定量标准与之对应.作者以福建省地震监测台网记录到的福建顺昌ML4.9地震和永春ML4.7地震为例采用以上震动烈度标准进行了分析计算,并与其他烈度计算方法及现场烈度调查结果进行比较,说明利用地震台网资料快速评定震动烈度的思路是可行的,评定结果可为政府应急救灾和民众了解大致震害程度提供重要信息.     

基于BP神经网络模型的多层砖房震害预测方法

针对传统的基于地震烈度的建筑物震害预测方法的不足,本文以地震动峰值加速度作为建筑物震害预测的地震动指标,结合几次大地震中多层砖房的震害实例,提出了一种基于BP神经网络模型的建筑物震害预测方法,模型的输入为反映结构抗震性能的各类物理参数,输出为给定地震动峰值加速度下建筑物破坏状态的概率。研究表明:基于BP网络模型的多层砖房的震害预测结果与震害实例的实际情况比较吻合,本文的思路和方法可推广于其他不同类型的建筑结构的震害预测。     

国家测震台网中心强震动数据处理系统的设计与实现

为满足国家测震台网海量强震动观测数据的处理时效性、格式标准化、产品丰富度等需求,开发了兼容多类强震动观测站点且具备数据快速汇集、处理及归档等功能的强震动数据处理系统。该系统提供地震波形人机交互数据预处理界面,对加速度记录进行预处理,进一步分析预处理后的加速度事件波形数据,计算得到地震动各项参数,包括峰值加速度(PGA)、峰值速度(PGV)、峰值位移(PGD)、仪器烈度、持时、傅氏谱、反应谱和三联谱等,可以导出地震元数据、地震记录波形,对各类数据进行归档存储。该系统具有平台统一性、功能集成性、数据完备性等特点,有效提升了日常数据处理和管理能力,能在地震应急、震害评估和科学研究中发挥实效。     

2013年木里、盐源交界地震震中区建筑物抗震性能分析

2013年11月22日,木里、盐源交界处先后发生Ms3.4、Ms 4.1及Ms3.7级地震,地震造成当地自建房屋破坏,震中区建筑类型主要为土木结构、夯土墙结构及木结构。本文在现场调查的基础上,对不同类型建筑物的破坏特征进行了分析,给出了地震烈度图,分析了建筑物破坏原因,指出土木结构及夯土墙结构是农村自建房屋中抗震最不利建筑,木结构房屋抗震性能相对较好。房屋抗震性能不佳是此次地震震害较重的主要原因。     

Damage to urban buildings in zones of intensities Ⅷ and Ⅶ during the Wenchuan earthquake and discussion on some typical damages

The outline and typical characteristics of damages to building in Jiangyou city and Anxian county(intensity VⅢ), Mianyang city and Deyang city(intensity VII) are introduced in the paper.The damage ratios, based on the sample statistics of multi-story brick buildings together with multi-story brick buildings with RC frame at first story(BBF), are presented.Then some typical damages, such as horizontal cricks of brick masonry buildings, X-shaped cricks on the walls under windows, the damages to columns, beams...     

Damage to urban buildings in zones of intensities Ⅷ and Ⅶ during the Wenchuan earthquake and discussion on some typical damages

The outline and typical characteristics of damages to building in Jiangyou city and Anxian county (intensity Ⅷ), Mianyang city and Deyang city (intensity Ⅶ) are introduced in the paper. The damage ratios, based on the sample statistics of multi-story brick buildings together with multi-story brick buildings with RC frame at first story (BBF), are presented. Then some typical damages, such as horizontal cricks of brick masonry buildings, Ⅹ-shaped cricks on the walls under windows, the damages to columns, beams and infill walls of frame buildings and the damage to half circle-shaped masonry walls, are discussed.     

冕宁县建筑物震害概率预测

本文在进行冕宁县建筑物普查和建筑物抗震性能抽样调查的基础上,采用建筑物单体及群体震害概率预测方法,对冕宁县进行震害预测,给出了50年内各镇及广大农村的建筑震害预测结果,为该县防震减灾提供了科学的依据。     

唐山地震桥梁震害回顾

对唐山桥梁震害加以回顾分析,并参照国内外地震有关桥梁的震害规律,为今后灾区破坏桥梁的修复和重建工作提供一些参考。     

Development and assessment of damage‐to‐loss models for moment‐frame reinforced concrete buildings

The assessment of earthquake loss often requires the definition of a relation between a measure of damage and a quantity of loss, usually achieved through the employment of a damage‐to‐loss model. These models are frequently characterized by a large variability, which inevitably increases the uncertainty in the vulnerability assessment and earthquake loss estimation. This study provides an insight on the development of damage‐to‐loss functions for moment‐frame reinforced concrete buildings through an analytical methodology. Tri‐dimensional finite element models of existing reinforced concrete buildings were subjected to a number of ground motion records compatible with the seismicity in the region of interest, through nonlinear dynamic analysis. These results were used to assess, for a number of damage states, the probability distribution of loss ratio, taking into consideration member damage and different repair techniques, as well as to derive sets of fragility functions. Then, a vulnerability model (in terms of the ratio of cost of repair to cost of replacement, conditional on the level of ground shaking intensity) was derived and compared with the vulnerability functions obtained through the combination of various damage‐to‐loss models with the set of fragility functions developed herein. In order to provide realistic estimates of economic losses due to seismic action, a comprehensive study on repair costs using current Portuguese market values was also carried out. The results of this study highlight important issues in the derivation of vulnerability functions, which are a fundamental component for an adequate seismic risk assessment. © 2015 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.     

The great historical 1755 earthquake. Effects and damage in Spain

The access to the complete reports sent in answer of a Royal enquire relative to the 1755 earthquake (Archivo Historico Nacional, 1756) provided us with information more comprehensive than that included in the analysis of such documents prepared by the Spanish Royal Academy of History in 1756 (Real Academia de la Historia, 1756). With such data, we have made a new study of the shock centred mainly in the following points: number of victims, source parameters (including moment magnitude and epicentral location),intensity map and seismogeological effects compared with those expected from the EMS-98. Relevant results from this analysis are: a new intensity attenuation law for earthquakes from the region of the 1755 shocks and first approximation damage probability matrices for buildings of the types common in the XVII to XIX centuries affected by large, distant earthquakes.     

Some considerations on the physical mea-sure of seismic intensity

Introduction In1564,an Italian man named Jacopo Gastaldi(XIE,1958)presented the first macroseismic intensity scale in the world,which based on the building damage and the ground surface failure after an earthquake.Today the seismic intensity has developed into an indispensable important concept,which applies to seismology and earthquake engineering,however it was just used to de-scribe earthquake damage while the concept of intensity was established.With this concept,seis-mologist can estima…     

Revision of seismic design codes corresponding to building damagesin the “5.12” Wenchuan earthquake

A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been updated. This paper briefly summarizes some of the major revisions that have been incorporated into the "Standard for classification of seismic protection of building constructions GB50223-2008" and "Code for Seismic Design of Buildings GB50011-2001." The definition of seismic fortification class for buildings has been revisited, and as a result, the seismic classifications for schools, hospitals and other buildings that hold large populations such as evacuation shelters and information centers have been upgraded in the GB50223-2008 Code. The main aspects of the revised GB50011-2001 code include: (a) modification of the seismic intensity specified for the Provinces of Sichuan, Shanxi and Gansu; (b) basic conceptual design for retaining walls and building foundations in mountainous areas; (c) regularity of building configuration; (d) integration of masonry structures and precast RC floors; (e) requirements for calculating and detailing stair shafts; and (f) limiting the use of single-bay RC frame structures. Some significant examples of damage in the epicenter areas are provided as a reference in the discussion on the consequences of collapse, the importance of duplicate structural systems, and the integration of RC and masonry structures.     

Field Signatures of the SE-Asian Mega-Tsunami along the West Coast of Thailand Compared to Holocene Paleo-Tsunami from the Atlantic Region

The Andaman-Sumatra Tsunami of Dec. 26, 2004, was by far the largest tsunami catastrophe in human history. An earthquake of 9 to 9.3 on the Richter scale, the extension of waves over more than 5000 km of ocean and run-ups up to 35 m are its key features. These characteristics suggest significant changes in coastal morphology and high sediment transport rates. A field survey along the west coast of Thailand (Phuket Island, Khao Lak region including some Similan Islands, Nang Pha mangrove areas and Phi Phi Don Islands) seven to nine weeks after the tsunami, however, discovered only small changes in coastal morphology and a limited amount of dislocated sediments, restricted to the lower meters of the tsunami waves. This is in striking contrast to many paleo-tsunami's events of the Atlantic region. Explanations for this discrepancy are sought in: a. Mechanics of the earthquake. A rather slow shock impulse on the water masses over the very long earthquake zone, b. Shallow water in the earthquake zone, and c. Bathymetry of the foreshore zone at the impacted sites. Shallow water west of Thailand has diminished wave energy significantly. The differences in geomorphological and sedimentological signatures of this tsunami compared with many paleo-tsunami worldwide makes it unsuitable to be used as a model for old and future tsunami imprints by an event of this extreme energy and extension.