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1.
Existing buildings can be at a greater seismic risk due to non-conformance to current design codes and may require structural retrofitting to improve building performance. The performance of buildings is measured in terms of immediate consequences due to direct damage, but the continuing impacts related to recovery are not considered in seismic retrofit assessment. This paper introduces a framework of retrofit selection based on the seismic resilience of deficient buildings retrofitted with the conventional mitigation approaches. The assembly-based methodology is considered for the seismic resilience assessment by compiling a nonlinear numerical model and a building performance model. The collapse fragility is developed from the capacity curve, and the resulting social, economic, and environmental consequences are determined. The seismic resilience of a building is assessed by developing a downtime assessment methodology incorporating sequence of repairs, impeding factors, and utility availability. Five functionality states are developed for the building functionality given investigated time interval, and a functionality curve for each retrofit is determined. It is concluded that seismic resilience can be used as a performance indicator to assess the continuing impacts of a hazard for the retrofit selection. 相似文献
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重要性不同的现有结构抗震加固设计地震动参数研究 总被引：1，自引：0，他引：1
提出了重要性不同的现有结构抗震加固设计基准期取值原则,给出了现有结构抗震加固设防水准的定义。基于地震危险性特征分区,利用地震动参数的危险性曲线公式对重要性不同的现有结构抗震加固设计地震动参数进行了分析。同时,为了便于工程设计人员使用,给出了现有结构设计地震动参数取值的简化方法。最后,通过算例解释了理论方法和简化计算方法中抗震加固设计地震动参数的取值方法和步骤。 相似文献
4.
Seismic isolation technique is increasingly used both for the design of new buildings and for the seismic retrofit of existing buildings. Nevertheless, so far, little attention has been paid on the collapse capacity of these structures, mainly because it requires refined nonlinear models and careful consideration of different sources of uncertainties. To fill this gap, a set of collapse fragility functions for existing reinforced concrete-frame buildings, designed for gravity loads only and then retrofitted with different isolation systems (including rubber-based and friction-based isolation systems), are derived in this study. For completeness, buildings with low and high seismic resistance are also considered. Collapse fragility functions are derived through incremental dynamic analysis, considering different collapse conditions both for isolation system and superstructure. For each case study building, mean and dispersion values are obtained considering both aleatory and epistemic uncertainties, due to record-to record and model variability, respectively. Finally, some comments on the possible use of the results of this study for practical applications are made. 相似文献
5.
Seismic safety of low ductility structures used in Spain 总被引：1，自引：0，他引：1
The most important aspects of the design, seismic damage evaluation and safety assessment of structures with low ductility
like waffle slabs buildings or flat beams framed buildings are examined in this work. These reinforced concrete structural
typologies are the most used in Spain for new buildings but many seismic codes do not recommend them in seismic areas. Their
expected seismic performance and safety are evaluated herein by means of incremental non linear structural analysis (pushover
analysis) and incremental dynamic analysis which provides capacity curves allowing evaluating their seismic behavior. The
seismic hazard is described by means of the reduced 5% damped elastic response spectrum of the Spanish seismic design code.
The most important results of the study are the fragility curves calculated for the mentioned building types, which allow
obtaining the probability of different damage states of the structures as well as damage probability matrices. The results,
which show high vulnerability of the studied low ductility building classes, are compared with those corresponding to ductile
framed structures. 相似文献
6.
城市所处的地震危险性环境和城市建筑物的易损性是影响复杂网络建筑物强震环境下抗毁能力的关键因素。由于现阶段对建筑物抗震抗毁能力的评定仍存在一定困难,对建筑物震害程度测评只能通过强震之后建筑物受破坏的程度进行评估,且评估结果不够精准,因此提出基于复杂网络的建筑物抗震能力的评估方法。考虑到地震中的危险性因素,以地面峰值加速度为参数对强震环境下复杂网络建筑物抗毁性进行测评和分析,在此基础上提出对复杂网络下建筑物的防震抗毁能力进行评估的相对建筑物抗震性能指数,并结合建筑物抗震能力评估标准确定其抗震能力水平;再进行仿真实验加以测量,并结合震害经验,证实该方法的有效性。 相似文献
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This study describes the seismic performance of an existing five storey reinforced concrete building which represents the typical properties of low-rise non-ductile buildings in Turkey. The effectiveness of shear walls and the steel bracings in retrofitting the building was examined through nonlinear static and dynamic analyses. By using the nonlinear static analysis, retrofitted buildings seismic performances under lateral seismic load were compared with each other. Moreover, the performance points and response levels of the existing and retrofitting cases were determined by way of the capacity-spectrum method described in ATC-40 (1996). For the nonlinear dynamic analysis the records were selected torepresent wide ranges of duration and frequency content. Considering the change in the stiffness and the energy dissipation capacities, the performance of the existing and retrofitted buildings were evaluated in terms of story drifts and damage states. It was found that each earthquake record exhibited its own peculiarities, dictated by frequency content, duration, sequence of peaks and their amplitude. The seismic performance of retrofitted buildings resulted in lower displacements and higher energy dissipation capacity depending mainly on the properties of the ground motions and the retrofitting strategies. Moreover, severe structural damage (irreparable or collapse) was observed for the existing building. However, buildings with retrofit alternatives exhibited lower damage levels changing from no damage to irreparable damage states. 相似文献
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This paper deals with the development of a procedure aimed at defining a seismic risk mitigation strategy for public buildings in terms of prioritization, time required and funds. The procedure is based on a global risk index involving the entire building stock under study thus facilitating an examination of risk variation over time up to its final value. Relationships between the current seismic capacity–demand ratios and the required strengthening costs (cost models) have been developed. Each of the assumed cost models has a different target in terms of capacity–demand ratio to be obtained after strengthening, basically ranging between full retrofit and upgrading. The procedure has been applied to 69 hospital buildings located in Basilicata region for which the vulnerability data was available as a result of a large assessment program set up by the regional government. Priorities have been defined on the basis of seismic capacity, local hazard and number of human beings possibly involved (exposure). The results of different strengthening strategies have been outlined with a special focus on the pros and cons of the upgrading strategy with respect to various retrofit strategies. The procedure may be applied to different categories of public buildings by properly modifying some input parameters and partially redefining criteria for prioritization. 相似文献
9.
In recent years, several research groups have studied a new generation of analysis methods for seismic response assessment of existing buildings. Nevertheless, many important developments are still needed in order to define more reliable and effective assessment procedures. Moreover, regarding existing buildings, it should be highlighted that due to the low knowledge level, the linear elastic analysis is the only analysis method allowed. The same codes (such as NTC2008, EC8) consider the linear dynamic analysis with behavior factor as the reference method for the evaluation of seismic demand. This type of analysis is based on a linear-elastic structural model subject to a design spectrum, obtained by reducing the elastic spectrum through a behavior factor. The behavior factor (reduction factor or q factor in some codes) is used to reduce the elastic spectrum ordinate or the forces obtained from a linear analysis in order to take into account the non-linear structural capacities. The behavior factors should be defined based on several parameters that influence the seismic nonlinear capacity, such as mechanical materials characteristics, structural system, irregularity and design procedures. In practical applications, there is still an evident lack of detailed rules and accurate behavior factor values adequate for existing buildings. In this work, some investigations of the seismic capacity of the main existing RC-MRF building types have been carried out. In order to make a correct evaluation of the seismic force demand, actual behavior factor values coherent with force based seismic safety assessment procedure have been proposed and compared with the values reported in the Italian seismic code, NTC08. 相似文献
10.
消能减震技术用于C类框架学校建筑提高一度抗震设防加固的探讨 总被引：1，自引：0，他引：1
针对既有的C类框架学校建筑提高一度抗震设防的加固目标,从地震作用计算、结构抗震验算和抗震构造措施等方面详细分析了其中的加固难点,指出了应用传统抗震加固方法的一些不足之处,探讨了应用消能减震技术进行结构提高一度抗震设防加固的可行性;并以某C类框架学校建筑加固工程为实例,从减震控制效果分析、弹塑性变形验算、消能部件影响评价、抗震构造措施核查4个方面论证了消能减震加固方法的有效性和可操作性。结果表明,消能减震技术在C类框架学校建筑抗震加固中具有一定的应用优势,不但能有效控制结构的地震响应,而且依据减震效果可以适当降低结构的抗震构造要求。因此,只要通过合理的消能减震加固设计,再辅以额外的局部加强处理,完全可以实现C类框架学校建筑提高一度抗震设防的加固目标需求。 相似文献
11.
This paper presents an analytical study aimed at evaluating the feasibility of using buckling-restrained braces as a retrofit scheme for existing multi-bay multi-story steel buildings. For that purpose, the seismic response of four two-dimensional frame models representative of typical steel buildings designed in a region of high seismicity was analyzed prior to and after including buckling-restrained braces as a retrofit strategy. The braces were designed following Force-Based and Displacement-Based approaches. The structural performance of the different versions of the frames was evaluated by subjecting each one to a set of twenty ground motions representative of the design earthquake with 10% exceedance probability in fifty years. It was observed that buckling-restrained braces allow for an efficient reduction in the peak drift demands in the retrofitted frames. However, since the beneficial effect of the braces cannot be fully controlled under a Force-Based design approach, it was concluded that a Displacement-Based design approach is the best option to achieve optimum structural performance. 相似文献
12.
In situ experiment on retrofit of school buildings by adding sandwich columns to partition brick walls 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Many significantly strong earthquakes have occurred over the years in Taiwan, which have caused tremendous damage to primary and middle school buildings; the 921 Chi‐Chi earthquake was particularly devastating. According to statistics, 786 schools (1,958 classrooms) were damaged on September 21, 1999 during this earthquake event. The devastation showed that a lack of seismic performance is a common problem for existing school buildings in Taiwan. Therefore, the retrofit of existing school buildings has become an urgent issue in the prevention of possible damage in the future. The retrofit technique of adding sandwich columns to partition brick walls is proposed in this paper, and the feasibility of the proposed method was verified by in situ pushover tests of two real school buildings, one without and one with retrofit. The experimental and analytical results show that the sandwich column itself contributes significantly to the seismic capacity of the examined school building. Moreover, the analytical results yielded conservative capacity curves when compared with the experimental results. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
13.
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. 相似文献
14.
The Himalayan region is one of the major seismic areas in the world. However, similar to many other seismically active locations, there are substantial numbers of unreinforced masonry(URM) buildings; the majority of which have not been designed for seismic loads. Past seismic events have shown that such buildings are highly vulnerable to earthquakes. Retrofitting of these URM buildings is an important concern in earthquake mitigation programs. Most government school buildings in rural areas of northern India are constructed of unreinforced masonry. These school buildings are socially important structures and serve as a crucial resource for rehabilitation during any disaster. The effectiveness of ferrocement(FC) to create a URM-FC composite is described in this study by estimating the performance and fragility of a URM school building before and after a retrofit. Analytical models, based on the equivalent frame method, are developed and used for nonlinear static analysis to estimate the enhancement in capacity. The capacity enhancement due to retrofitting is presented in terms of the maximum PGA sustained and damage probabilities at the expected level of earthquake hazard. 相似文献
15.
The seismic evaluation of existing buildings is a more difficult task than the seismic design of new buildings. Non-linear
methods are needed if realistic results are to be obtained. However, the application to real complex structures of various
evaluation procedures, which have usually been tested on highly idealized structural models, is by no means straightforward.
In the paper, a practice-oriented procedure for the seismic evaluation of building structures, based on the N2 method, is
presented, together with the application of this method to an existing multi-storey reinforced concrete building. This building,
which is asymmetric in plan and irregular in elevation, consists of structural walls and frames. It was designed in 1962 for
gravity loads and a minimum horizontal loading (2% of the total weight). The main results presented in terms of the global
and local seismic demands are compared with the results of non-linear dynamic response-history analyses. As expected, the
structure would fail if subjected to the design seismic action according to Eurocode 8. The shear capacity of the structural
walls is the most critical. If the shear capacity of these elements was adequate, the structure would be able to survive the
design ground motion according to Eurocode 8, in spite of the very low level of design horizontal forces. The applied approach
proved to be a feasible tool for the seismic evaluation of complex structures. However, due to the large randomness and uncertainty
which are involved in the determination of both the seismic demand and the seismic capacity, only rough estimates of the seismic
behaviour of such structures can be obtained. 相似文献
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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... 相似文献
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The paper describes the earthquake performance assessment of two historical buildings located in Istanbul exposed to a Mw = 7+ earthquake expected to hit the city and proposes solutions for their structural rehabilitation and/or strengthening.
Both buildings are unreinforced clay brick masonry (URM) structures built in 1869 and 1885, respectively. The first building
is a rectangular-shaped structure rising on four floors. The second one is L-shaped with one basement and three normal floors
above ground. They survived the 1894, Ms = 7.0 Istanbul Earthquake, during which widespread damage to URM buildings took place in the city. Earthquake ground motion
to be used in performance assessment and retrofit design is determined through probabilistic and deterministic seismic hazard
assessment. Strength characteristics of the brick walls are assessed on the basis of Schmidt hammer test results and information
reported in the literature. Dynamic properties of the buildings (fundamental vibration periods) are measured via ambient vibration
tests. The buildings are modelled and analyzed as three-dimensional assembly of finite elements. Following the preliminary
assessment based on the equivalent earthquake loads method, the dynamic analysis procedure of FEMA 356 (Pre-standard and commentary
for the seismic rehabilitation of buildings, American Society of Civil Engineers, Reston, 2000) and ASCE/SEI 41-06 (Seismic rehabilitation of existing buildings, American Society of Civil Engineers, Reston, 2007) is followed to obtain dynamic structural response of the buildings and to evaluate their earthquake performance. In order
to improve earthquake resistance of the buildings, reinforced cement jacketing of the main load carrying walls and application
of fiber reinforced polymer bands to the secondary walls are proposed. 相似文献
18.
The design code for each country is revised and updated based on an expected zone’s seismic intensities,geotechnical site classifications,structural systems,construction materials and methods of construction in order to provide more realistic considerations of seismic demand,seismic response,and seismic capacity.Based on the aforementioned provisions,structures designed according to different seismic codes may yield different performances for the same level of hazard.This study aims to investigate and compare the induced responses related to the earthquake-resistant design of reinforced concrete(RC)buildings according to the Saudi building code(SBC-301),American code(ASCE-7),uniform building code(UBC-97),and European code(EC-8).In order to account for the provision regarding the hazard specification and its effect on the induced seismic responses,four regions in the Kingdom of Saudi Arabia with different seismic levels are selected.The code provisions related to the specification of site classification and its effect on the induced design base shear are investigated as well.Significant differences are observed in the induced responses with the variation in seismic design codes for the considered seismic hazards and site classifications. 相似文献
19.
IntroductionAt present, the proper design and construction of buildings for earthquake-resistance is the most effective measure to mitigate the earthquake damage. In a broad sense, the earthquake resistance design should include the following seven contents:1) Determining the seismic design criteria Determining the seismic design goals3) Determining the seismic design parameters (intensity or ground motion) and their numerical values4) Determining the category of importance for buildings and … 相似文献
20.
利用多层砌体房屋震害预测专家系统,对山东潍坊地区１８２栋多层砖房逐栋进行了单体房屋的震害预测,在此基础上,统计分析了该地区多层砖房的地震易损性特征,并进行了初步震害预测研究,给出了该类房屋的易损性矩阵,各破坏等级的损失参数矩阵和对应不同地震烈度的相对损失预测,为进一步开展震害预测和采取地对性的防震减灾对策提供了科学依据。 相似文献