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1.
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   

2.
This paper deals with the period evaluation of Reinforced Concrete (RC) framed buildings in elastic, yield and severely damaged states. Firstly, period-height relationships either reported in the literature, or obtained from both numerical simulations (eigenvalue analyses) and experimental measurements (ambient vibration analyses) have been examined and compared. Structural types representing low-rise, mid-rise and high-rise RC buildings without earthquake resistant design, widely present in the Italian and European built environment, have been studied. Results have shown high differences between numerical and experimental period values. Period elongation (stiffness degradation) during and after strong ground shaking has been also examined based on results from experimental in situ and laboratory tests performed on some RC framed building structures which suffered moderate-heavy damage. Some comments on the relationship between damage level and period elongation are reported.  相似文献   

3.
Probabilistic fragility functions have been developed for low-rise, reinforced concrete buildings subjected to earthquake triggered slow-moving slides, applying a recently published methodology by the same authors [5] (Fotopoulou and Pitilakis, 2012). We performed an extensive numerical parametric study considering different idealized slope configurations, soil and geological settings, as well as distances of the structure to the slope's crest and foundation typologies. Various features of the structural damage are explored, highlighting trends on the building's behavior to the permanent co-seismic slope deformations. The proposed generalized probabilistic fragility curves have been developed as a function of the expected outcrop peak ground acceleration (PGA) as provided by modern seismic codes, i.e. EC8, or the induced permanent slope ground displacements (PGD) for different slope angles, water table level and soil type, foundation typology and seismic design code. Detailed sensitivity analyses of the above parameters, reveal their relative importance for the vulnerability analysis and the quantitative risk assessment of low-rise RC buildings subjected to earthquake triggered slow-moving slides.  相似文献   

4.
In May 2008 a shallow Mw6.3 earthquake struck South Iceland with an epicentre close to two small towns. Nearly 5000 low-rise residential buildings were affected. The recorded maximum PGA was 0.88 g. A great deal of damage occurred, but there was no loss of life. In Iceland all buildings are registered in a detailed official database and insurance against natural disasters is obligatory. As the repair costs for every affected building had to be assessed for insurance purposes this provided an unusual opportunity to review structural performance across the whole population of buildings in the affected area. The estimated repair cost was classified in a number of subcategories covering structural and non-structural damage for five different residential building typologies. Study of these buildings showed that non-structural damage dominated the overall damage. The main monetary damage was cosmetic damage of partition walls and flooring. The structural systems performed quite well and no buildings collapsed.  相似文献   

5.
This paper describes an analysis of damage costs to commercial and industrial property, including buildings (all low-rise), their contents, equipment and stock, in the Ms = 6.6 Edgecumbe New Zealand earthquake of 2 March 1987. The damage costs were converted to damage ratios by dividing by the value of the relevant property item. For the MM7 and MM9 intensity zones, the mean values and statistical distributions of these damage ratios were then found, the lognormal distribution fitting well. For all commercial and industrial buildings in the MM intensity IX zone (centroid MM9-4) the mean damage ratio was 0.076. The mean damage ratios were generally much smaller than estimated in previous studies. The buildings were all low-rise. There was no correlation between building and equipment damage ratios on a building by building basis. Considering dates of construction, it appears that mean damage levels at MM9 have not changed significantly for postcode buildings through changes in design standards up to the 1980s.  相似文献   

6.
Guo  Wei  Wu  Jun  Hu  Yao  Li  Yunsong  Yang  T. Y. 《地震工程与工程振动(英文版)》2019,18(2):433-446
Adding dampers is a commonly adopted seismic risk mitigation strategy for modern buildings, and the corresponding design procedure of dampers has been well established by the Chinese Building Code. Even though all types of dampers are designed by the same procedure, actual seismic performance of the building may differ from one to the others. In this study, a nine-story benchmark steel building is established, and three different and typical types of dampers are designed according to the Chinese Building Code to realize structural vibration control under strong earthquake excitation. The seismic response of the prototype building equipped with a viscoelastic damper, viscous damper and buckling-restrained brace(BRB) subjected to 10 earthquake records are calculated, and Incremental Dynamic Analysis(IDA) is performed to describe progressive damage of the structure under increasing earthquake intensity. In the perspective of fragility, it shows that the viscoelastic damper has the highest collapse margin ratio(CMR), and the viscous damper provides the best drift control. Both the BRB and viscoelastic dampers can effectively reduce the floor acceleration responses in the mid-rise building.  相似文献   

7.
In cities and urban areas, building structures located at close proximities inevitably interact under dynamic loading by direct pounding and indirectly through the underlying soil. Majority of the previous adjacent building pounding studies that have taken the structure–soil–structure interaction (SSSI) problem into account have used simple lumped mass–spring–dashpot models under plane strain conditions. In this research, the problem of SSSI‐included pounding problem of two adjacent symmetric in plan buildings resting on a soft soil profile excited by uniaxial earthquake loadings is investigated. To this end, a series of SSSI models considering one‐directional nonlinear impact elements between adjacent co‐planar stories and using a method for direct finite element modeling of 3D inelastic underlying soil volume has been developed to accurately study the problem. An advanced inelastic structural behavior parameter, the seismic damage index, has been considered in this study as the key nonlinear structural response of adjacent buildings. Based on the results of SSSI and fixed base case analyses presented herein, two main problems are investigated, namely, the minimum building separation distance for pounding prevention and seismic pounding effects on structural damage in adjacent buildings. The final results show that at least three times, the International Building Code 2009 minimum distance for building separation recommended value is required as a clear distance for adjacent symmetric buildings to prevent the occurrence of seismic pounding. At the International Building Code‐recommended distance, adjacent buildings experienced severe seismic pounding and therefore significant variations in storey shear forces and damage indices. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

8.
青海省共和地区位于柴达木—阿尔金地震带内,具备发生中强地震的构造背景,近年来该地区地震活动频繁,农村地区受经济和技术等条件的限制,造成了巨大的人员伤亡和经济损失。为深入了解共和地区农村民居结构特征与抗震性能现状,开展实地调查,基于历史震害资料,总结区域内典型农村民居震害特点,并进行震害预测,得到不同地震烈度下农村民居不同的破坏结果。结果表明:青海省共和地区农村民居中的砖混结构和砖木结构房屋数量约占48%、47%,其中约68%砖混结构房屋未设置构造柱和圈梁等抗震设防措施;该地区主要农村民居基本达到Ⅶ度抗震设防要求,仅部分建造年代久的土木结构房屋破坏严重;地震烈度为Ⅷ度时,大部分房屋以中等破坏和严重破坏为主;地震烈度为Ⅸ、Ⅹ度时,农村民居将发生大范围严重破坏,甚至毁坏。  相似文献   

9.
The majority of existing buildings are not safe against earthquakes in most of the developing countries. Existing building stocks should be assessed with a seismic safety assessment method before a devastating earthquake. Cheaper and quicker rapid seismic safety assessment methods can be used instead of code-based assessment methods to determine the seismic performance of existing buildings. In this study, an approach was introduced to determine the seismic performance of existing mid-rise reinforced concrete buildings with fewer parameters and process steps than code-based detailed assessment procedures. Calibration and regulation of the introduced method were conducted on the 39 collapsed buildings’ projects in 1999 Kocaeli, Turkey, earthquake. Finally, 55 existing buildings located in Eskisehir, Turkey, assessed with this calibrated method and the results were compared with the results of a code-based detailed assessment method; the results showed a very good agreement of about 83%. This study shows that the proposed method can be applied for the determination of the seismic performance of existing mid-rise reinforced concrete buildings quickly and without compromising reliability.  相似文献   

10.
This study presents a seismic fragility analysis and ultimate spectral displacement assessment of regular low-rise masonry infilled (MI) reinforced concrete (RC) buildings using a coefficient-based method. The coefficient-based method does not require a complicated finite element analysis; instead, it is a simplified procedure for assessing the spectral acceleration and displacement of buildings subjected to earthquakes. A regression analysis was first performed to obtain the best-fitting equations for the inter-story drift ratio (IDR) and period shift factor of low-rise MI RC buildings in response to the peak ground acceleration of earthquakes using published results obtained from shaking table tests. Both spectral acceleration-and spectral displacement-based fragility curves under various damage states (in terms of IDR) were then constructed using the coefficient-based method. Finally, the spectral displacements of low-rise MI RC buildings at the ultimate (or near-collapse) state obtained from this paper and the literature were compared. The simulation results indicate that the fragility curves obtained from this study and other previous work correspond well. Furthermore, most of the spectral displacements of low-rise MI RC buildings at the ultimate state from the literature fall within the bounded spectral displacements predicted by the coefficient-based method.  相似文献   

11.
Performance of masonry buildings during the Emilia 2012 earthquake   总被引：2，自引：2，他引：0  
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.  相似文献   

12.
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   

13.
地震对建筑结构的损伤轻则影响建筑完整性,重则导致建筑崩塌。近几年,地震损伤评估问题得到地震工程研究领域的高度重视,但对点支式玻璃建筑结构的损伤评估研究较少。为此,构建一种点支式玻璃建筑结构地震损伤评估模型。采用基于HHT变换的结构损伤部位识别方法判断地震中点支式玻璃建筑损伤部位,建立点支式玻璃建筑结构地震损伤评估多元联系数模型,评估点支式玻璃建筑损伤部位的损伤情况。结果表明,该评估模型对某地区点支式玻璃建筑结构地震损伤评估情况与实际结果一致,且该模型可控性较强,评估范围全面,评估效率明显优于其他评估模型,应用价值较高。  相似文献   

14.
This study focuses on the seismic safety evaluation of masonry buildings in Turkey for in‐plane failure modes using fragility curves. Masonry buildings are classified and a set of fragility curves are generated for each class. The major structural parameters in the classification of masonry buildings are considered as the number of stories, load‐bearing wall material, regularity in plan and the arrangement of walls (required length, openings in walls, etc.), in accordance with the observations from previous earthquakes and field databases. The fragility curves are generated by using time history (for demand) and pushover (for capacity) analyses. From the generated sets of fragility curves, it is observed that the damage state probabilities are significantly influenced from the number of stories and wall material strength. In the second stage of the study, the generated fragility curves are employed to estimate the damage of masonry buildings in Dinar after the 1995 earthquake. The estimated damage by fragility information is compared with the inspected visual damage as assessed from the Damage Evaluation Form. For the quantification of fragility‐based damage, a single‐valued index, named as ‘vulnerability score’ (VS), is proposed. There seems to be a fair agreement between the two damage measures. In addition to this, decisions regarding the repair or demolition of masonry buildings in Dinar due to visual damage inspection are on comparable grounds with the relative measure obtained from VS of the same buildings. Hence, the fragility‐based procedure can provide an alternative for the seismic safety evaluation of masonry buildings in Turkey. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

15.
We have tried to estimate the yield shear strengths of reinforced concrete (RC) buildings based on the damage statistics in Kobe surveyed after the Hyogo‐ken Nanbu, Japan, earthquake of 1995 and the non‐linear response analyses for synthetic waveforms calculated from a complex seismic source and a three‐dimensional basin structure. First, a set of building models that represented the RC building stock in Kobe was constructed and plausible non‐linear multi‐degree‐of‐freedom models with four different numbers of stories were created based on the current seismic code and construction practice. For response analysis the damage criterion and the strength distribution should be assumed a priori. When the damage ratios for these standard models were calculated it was found that the damage ratios were so high that we had to increase the average yield strengths in order to match the calculated damage ratios to those observed. After searching the best models it was found that the estimated average yield strengths should be much higher than those based on the code, especially for low‐rise buildings. Using this set of building models we succeeded in reproducing the belt‐shaped area with high damage ratios in Kobe. One can apply the proposed methodology to different countries if there is enough damage data, strong motion records, and building statistics. If there is sparse damage data at several locations only, then our models can be adjusted to reproduce observed damage data and used for damage prediction as a first‐order approximation. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

16.
The city of Oran is exposed to a significant seismic hazard, as almost all the northern Algeria territory, where numerous casualties and severe damage occurred in the last decades due to several moderate to large earthquakes. A mitigation policy should include the establishment of priorities to reduce the vulnerability of existing buildings based on the knowledge of the actual urban fabrics. The complexity of vulnerability assessment requires a gradual approach from the urban scale to the building scale. The study reported in this paper corresponds to the first step of such an approach, i.e., a preliminary study of the seismic vulnerability and expected damage within an urban district of the city of Oran, based on a non-dedicated data base from a building survey previously performed for other purposes. The main goals of this study are twofold: (1) an assessment of the degree of uncertainty and robustness of such results through a comparison of the results derived from different urban vulnerability methods (GNDT 2; RISK-UE LM1; and VULNERALP 2.0) and (2) an assessment of the actual level of seismic risk in the city of Oran. Cross-method comparisons and correlations highlight a satisfactory agreement between mean damage estimates at the urban scale, despite significant scattering at the single building scale, and uncertainty levels which vary significantly from one method to the other. For a given scenario, the three methods provide damage estimates lying within half an EMS damage degree of one another, with some systematic positive bias for VULNERALP and negative bias for RISK-UE LM1, especially for masonry buildings. The expected mean damage is very important for intensities 9 and 10, with an average damage grade around 3–4 for intensity 9 and 4–5 for intensity 10. The spatial distribution of damage systematically exhibits larger values in the northern, older, commercial area, than in the southern, more recent and more residential area, in relation to the building typology and the existence of several aggravating factors. Some areas of higher vulnerability / damage can be distinguished, which should receive particular attention for retrofitting priorities or urban planning decisions, also taking into account their cultural heritage value.  相似文献   

17.
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.  相似文献   

18.
史华 《地震工程学报》2017,39(6):1024-1028
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   

19.
On March 1993 an earthquake of magnitude Ms = 5·5 shook Pyrgos, a town in Western Peloponnissos, one of the most seismic prone areas in Greece. The damage induced to modern reinforced concrete buildings was rather light in contrast to the damage induced to historic and traditional buildings of adobe, stone or brick masonry which was severe. In order to study the causes of structural damage, detailed data are collected from a rather large statistical sample of 1023 masonry buildings and 22 reinforced concrete framed buildings with visible damage. For each building the number of storeys, the material of construction, as well as the type and the degree of damage are recorded. In addition, consideration is given to the site of the building within the town and the corresponding soil conditions. For reinforced concrete buildings, damage occured mostly in areas with relatively high estimated spectral accelerations and fundamental soil periods of vibration close to those of the buildings. Nevertheless, further analysis is required to explain the selective damage of a very small number of buildings. For masonry houses, the effect of soil conditions is more systematic. Moreover, the effects of the number of storeys as well as the age and material of construction appear to be dominant.  相似文献   

20.
陈波  谢俊举  温增平 《地震学报》2013,35(2):250-261
研究了具有不同自振特性的建筑结构在近断层速度脉冲型及非速度脉冲型地震动作用下的结构层间变形分布,揭示了近断层速度脉冲对工程结构地震响应的特殊影响. 从汶川MS8.0地震近断层强震记录中选取两组典型速度脉冲型记录和非脉冲型记录, 根据确定的目标地震动强度水平,利用时域叠加小波函数法对选择的强震记录进行调整, 使之与目标地震动水平对应的加速度反应谱保持一致, 以此作为结构地震反应分析的地震动输入. 选取具有不同自振特征的3层、11层和20层典型钢筋混凝土框架结构, 建立有限元分析模型, 分别计算在速度脉冲型与非速度脉冲型记录作用下这些结构层间变形分布. 研究表明,速度脉冲型记录与非速度脉冲型记录作用下结构层间变形有明显差异, 且与结构自振特征有关.就低层结构的层间变形而言, 非速度脉冲型记录的影响较速度脉冲型记录的影响大. 随着结构自振周期的增加, 高阶振型的影响更加明显. 与非速度脉冲型记录相比,速度脉冲型记录的结构层间位移反应中值及离散程度较大. 速度脉冲型记录更容易激发高层结构的高阶振型, 产生较大的层间位移反应. 非速度脉冲型记录对中低层结构层间变形影响较大.因此, 在开展近断层结构地震影响评价时, 应考虑近断层速度脉冲的影响.   相似文献   

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