Study on vulnerability matrices of masonry buildings of mainland of China

The degree and distribution of damage to buildings subjected to earthquakes is a concern of the Chinese Government and the public.Seismic damage data indicates that seismic capacities of different types of building structures in various regions throughout mainland of China are different.Furthermore,the seismic capacities of the same type of structure in different regions may vary.The contributions of this research are summarized as follows:1)Vulnerability matrices and earthquake damage matrices of masonry structures in mainland of China were chosen as research samples.The aim was to analyze the differences in seismic capacities of sample matrices and to present general rules for categorizing seismic resistance.2)Curves relating the percentage of damaged masonry structures with different seismic resistances subjected to seismic demand in different regions of seismic intensity(VI to X)have been developed.3)A method has been proposed to build vulnerability matrices of masonry structures.The damage ratio for masonry structures under high-intensity events such as the Ms 6.1 Panzhihua earthquake in Sichuan province on 30 August2008,was calculated to verify the applicability of this method.This research offers a significant theoretical basis for predicting seismic damage and direct loss assessment of groups of buildings,as well as for earthquake disaster insurance.     

Empirical seismic vulnerability analysis for masonry buildings based on school buildings survey in Iran

School facilities in Iran, in particular masonry schools, have shown poor performance during past earthquakes and can be identified as one of the parts of the country’s infrastructure that is most vulnerable to earthquakes. Hence, in this paper a method to perform index-based damage assessment for brick masonry schools located in the province of Yazd, the central region of Iran, using a comprehensive database of school buildings, is proposed. The database was obtained from the field survey forms applied for each observed school to collect the features of and damage to the structure. The results of a vulnerability index method developed in Iran are employed as input data to obtain empirical fragility curves for the school inventory. The Macroseismic model and GNDT II level method are two empirical methods combined in this procedure. Finally, the procedure is verified using damage survey data obtained after recent earthquakes (1990 Manjil–Rudbar earthquake and 2003 Bam earthquake) that occurred in Iran.     

Seismic vulnerability assessment and fragility analysis of pre-code masonry buildings in Portugal

Bulletin of Earthquake Engineering - Despite the fact that in recent years Portugal has not seen the occurrence of high-magnitude earthquakes, it remains threatened by these events due to its...     

砌体结构损伤检测的脉动法

应用脉动法测到的信号分析结构的固有频率和振型，利用作者提出的改进的单纯形法来识别结构刚度。根据识别的刚度矩阵，利用结构刚度与层间抗压抗剪强度、砂浆强度之间的关系，则可求得砌体的强度，从而达到对砌体结构进行损伤检测和安全性评定的目的。对某七层砌体结构进行实例，结果表明该方法能够比较准确地对砌体结构进行损伤检测和安全性评定。     

Shaking table tests on 24 simple masonry buildings

The paper presents the results of a large experimental programme carried out on models, scaled 1:2, of two-storey masonry buildings. After suffering damage, the models were repaired and strengthened and tested again. A total of 24 buildings were subjected to 119 shaking-table tests, by ISMES (Italy) and LEE (Greece) facilities. The results allow to assess the efficiency of the various strengthening techniques employed and to describe the change of dynamic properties of the systems at the increase of damage. © 1998 John Wiley & Sons, Ltd.     

多层错层砖砌体房屋抗震分析

本文根据典型的东西和南北错层单元模型,按不同的错层高度、不同收层情况和不同理置深度的实际房屋情况,分析建立了错层房层和相应的等效规整房屋模型,采用板壳单元,用有限元方法计算了这些模型的动力特征和在地震作用下的墙肢剪应力分布,经过对比分析得到了一些错层房屋墙应力的分布规律。根据错层房屋的受力特点,文中提出了相应的加强构造措施,结构布置要求和错层房屋的抗震计算模型等具体建议。     

配筋砌体结构地震易损性评价方法初探

本文首先简要介绍了考虑空间协同的配筋砌体结构弹塑性地震反应分析程序EDAPSC；然后提出了一种利用空间协同时程分析结果，对配筋砌体结构地震易损性进行定量评价的方法，并以上海园南小区住宅楼为例进行了地震易损性分析，说明本文提出的地震易损性评价方法是可行和合理的；另外作者还对设计人员提出了提高结构抗震安全性的建议。     

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.     

On the vulnerability assessment of monumental buildings

In all European countries the will to conserve the building heritage is very strong. Unfortunately, large areas in Europe are characterised by a high level of seismic hazard and the vulnerability of ancient masonry structures is often relevant. The large number of monumental buildings in urban areas requires facing the problem with a methodology that can be applied at territorial scale, with simplified models which need little easily obtainable, data. Within the Risk-UE project, a new methodology has been stated for the seismic vulnerability assessment of monumental buildings, which considers two different approaches: a macroseismic model, to be used with macroseismic intensity hazard maps, and a mechanical based model, to be applied when the hazard is provided in terms of peak ground accelerations and spectral values. Both models can be used with data of different reliability and depth. This paper illustrates the theoretical basis and defines the parameters of the two models. An application to an important church is presented.     

Non-linear static analysis of masonry buildings based on a strut-and-tie modeling

This paper presents an analytical method for evaluating the capacity curve of masonry buildings according to non-linear static analysis. This method splits the building into stories, and the vertical structures of each story into masonry panels, which are analyzed individually by a new push-over analysis. The behavior of each panel is reproduced with an evolutive strut-and-tie model, which simulates the uncracked and cracked behavior of the panel subjected to a vertical constant force and a lateral force that increases up to the complete development of the failure mechanism. The strut-and-tie model provides the capacity curve of the panel. The composition of the capacity curves of all the panels of a story provides the capacity curve of this story. The capacity curves of all the stories of the building can be used to obtain either the maximum drift that the building can withstand or the behavior factor of the structure. Either outcome allows the specific dissipation capacity and overstrength of the masonry building to be considered in the seismic analyses, which provides ultimate limit state verifications with more reliability.The proposed method is applied to a school building. The comparison between seismic safety assessed with this method and with a linear dynamic analysis, all other parameters being equal, shows that the latter approach is overly-conservative and misleading. In fact, the specific inelastic capacity, which only the former approach can consider, influences greatly the seismic behavior of the case study.     

Performance of masonry buildings during the Emilia 2012 earthquake

The earthquake sequence started on May \(20\) th 2012 in Emilia (Italy) affected a region where masonry constructions represent a large part of the existing building stock and the construction of new modern masonry buildings is a common practice. The paper is focused on the performance of common architectural configurations, typical for residential or business use. The large majority of old masonry buildings is made of fired clay bricks. The seismic performance of these buildings is particularly interesting since major past earthquakes in Italy affected areas with mainly stone masonry structures. Apart from examples showing systematic or peculiar structural deficiencies governing the vulnerability of several buildings, the overall seismic performance of these structures to repeated shaking, with PGA as large as 0.25–0.3 g was rather good, despite the major part of them were only conceived for carrying vertical loads. In fact, seismic design is mandatory in the area only since 2003. Modern low-rise masonry buildings erected after this date and incorporating seismic design and proper detailing resulted in most cases practically undamaged. The examples reported in the paper allow an evaluation of the superior performance of seismically designed modern masonry buildings in comparison to older ones.     

Modelling methods of historic masonry buildings under seismic excitation

Historic masonry buildings in seismically active regions are severely damaged by earthquakes, since they certainly have not been explicitly designed by the original builders to withstand seismic effects, at least not in a ‘scientific’ way from today’s point of view. The assessment of their seismic safety is an important first step in planning the appropriate interventions for improving their pertinent resistance. This paper presents a procedure for assessing the seismic safety of historic masonry buildings based on measurements of their natural frequencies and numerical simulations. The modelling of the brittle nonlinear behaviour of masonry is carried out on the macro-level. As an example, a recently completed investigation of the seismic behaviour of the Aachen Cathedral is given, this being the first German cultural monument to be included in the UNESCO cultural heritage list in 1978. Its construction goes back to the 9th century a.d. and it is considered as one of the finest examples of religious architecture in Central Europe. The investigation is based on measurements of the natural frequencies at different positions and numerical simulations using a detailed finite element model of the Cathedral.     

多层砌体房屋抗震加固方法述评

本文讨论了多层砌体房屋抗震加固的原则,对目前常用的多层砌体房屋的加固方法进行了简要的论述,提出了各种方法的特点和适用范围以及需要注意的问题,并指出了将来可能的发展方向。     

考虑抗倒能力的砌体结构震害预测

以往对砌体结构的抗震鉴定或震害预测方法没有考虑构造柱、圈梁等抗震措施对增强砌体结构抗倒能力的影响,使得在高烈度下的鉴定或震害预测结果多为倒塌,这与震害实际不符合。实际在高烈度区,有一些砌体结构并没有倒塌。本文按照杨玉成等[1]提出的用抗倒增强系数修正楼层综合抗震能力指数方法,将抗倒增强系数的取值推广到不同工况;提出地震烈度为Ⅹ度时烈度影响系数为4.0;推演了杨玉成等提出的用综合抗震能力指数表示的震害预测判别标准。按此法进行了24栋建筑的分析,震害预测结果显示考虑抗倒能力的方法适用于高烈度下的砌体结构震害预测,简单易用,符合震害实际。     

Effect of out-of-plane behavior on seismic fragility of masonry buildings in Turkey

This study focuses on the evaluation of seismic safety of unreinforced masonry buildings in Turkey by using fragility curves generated for two behavior modes of load bearing walls: in-plane and out-of-plane. During generation of fragility curves, a force-based approach has been used. There exist two limit states in terms of base shear strength for in-plane behavior mode and flexural strength for out-of-plane behavior mode. To assess the seismic vulnerability of unreinforced masonry buildings in Turkey, fragility curves generated for in-plane behavior were verified by the observed damage during the 1995 Dinar (Turkey) earthquake and fragility curves generated for out-of-plane behavior were verified by the observed damage during the 2010 Elaz?? (Turkey) earthquake. The verification results reveal that the proposed fragility-based procedure can provide an alternative for the seismic safety evaluation of unreinforced masonry buildings in Turkey. Using this procedure, it becomes possible to investigate a large population of masonry buildings located in regions of high seismic risk in a short period of time. The obtained results are valuable in the sense that they can be used as a database during the development of strategies for pre-earthquake planning and risk mitigation for earthquake prone regions of Turkey.     

Evaluation of the seismic response of masonry buildings based on energy functions

This work is based on energies evaluated from the responses of 12 stone and brick masonry systems subjected to 58 shaking table tests. The evolution of input energy during a damaging base excitation is correlated to the change of the damage patterns of the considered buildings. The comparison among energies dissipated and absorbed by the buildings during the various shocks gives some hints on strengthening strategies. It is found that damage to spandrel beams produces a more significant energy absorption than other types of damage. Copyright © 2001 John Wiley & Sons, Ltd.     

多层住宅砖房的地震易损性分析

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。