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1.
选取按照现行规范设计的既有建筑进行有限元建模,考虑地震动的不确定性对其进行大量增量动力分析(IDA),得到模型的IDA曲线簇。在此基础上对其进行地震需求概率分析和概率抗震能力分析,拟合得到结构的易损性曲线,据此对结构的倒塌概率进行定量评估,并比较基于非线性分析与性能评估软件PERFORM-3D的纤维模型和塑性铰模型的分析结果。结果表明:按照我国现行规范设计的钢筋混凝土(RC)框架结构,在预期的罕遇地震作用下倒塌概率较小,可满足"大震不倒"的要求;基于PERFORM-3D的截面纤维模型所得的RC框架结构,经非线性分析所得的倒塌概率相对保守,安全储备更高。 相似文献
2.
基于单一指标的传统地震易损性分析忽略了非结构构件损伤对建筑抗震性能的影响。首先基于多维性能极限状态理论建立了三维性能极限状态方程,并对几种特殊情况下的三维阈值曲面进行了讨论。进而以最大层间位移角作为整体结构与位移敏感型非结构构件的性能指标,以峰值楼面加速度作为加速度敏感型非结构构件的性能指标,对建筑的结构损伤和非结构损伤进行描述。考虑各性能指标之间的相关性和各性能指标所对应的极限状态阈值的不确定性,建立了建筑在地震作用下的三维性能极限状态的超越概率函数。最后,采用Open Sees有限元软件对一7层钢筋混凝土框架填充墙建筑进行增量动力分析,得到其各性能水平下的地震易损性曲线。分析结果表明,当忽略非结构构件损伤时,各性能极限状态的超越概率均降低,从而高估了建筑剩余功能水平,进而导致低估建筑的损失。在考虑各性能指标的极限状态阈值的不确定性时,对任一性能极限状态,不同变异系数取值下的易损性曲线会出现交点,在交点之前超越概率随着变异系数的增大而增大,交点之后则随着变异系数的增大而减小。在考虑性能指标间的相关性时,对任一性能极限状态,超越概率随着相关系数的减小而增大。另外,性能指标阈值的不确定性与性能指标间的相关性对地震易损性的影响随着性能水平的提高而逐渐降低,且对低性能水平下建筑地震易损性有明显影响。 相似文献
3.
Incremental dynamic analysis and nonlinear static pushover analysis are carried out on a performance-based design to determine the seismic demands and capacities of an elliptic braced moment resisting frame (ELBRF). The objective is to assess ductility, overstrength and response modification factors in a modern steel-braced structural system based on incremental dynamic analysis. This integrated system is connected to a beam and column with an appropriate length while providing enough architectural space to allow for an opening without having the common problems associated with architectural spaces in braced systems. Several different classes of buildings are considered on soil type II. Linear dynamic analysis, nonlinear static pushover analysis and incremental nonlinear dynamic analysis related to 12 records from past earthquakes are carried out using OpenSees software. The factors of ductility, overstrength and response modification are calculated for this system. The values of 9.5 and 6.5 are found and suggested only for the response modification factor for ELBRF systems in allowable stress and ultimate limit state methods, respectively. The fragility curves are plotted for the first time for this type of bracing, which contributes to the assessment of building seismic damage. 相似文献
4.
Forward directivity may cause large velocity pulses in ground motion time histories that are damaging to buildings at sites close to faults, potentially increasing seismic collapse risk. This study quantifies the effects of forward directivity on collapse risk through incremental dynamic analysis of building simulation models that are capable of capturing the key aspects of strength and stiffness degradation associated with structural collapse. The paper also describes a method for incorporating the effects of near-fault directivity in probabilistic assessment of seismic collapse risk. The analysis is based on a suite of RC frame models that represent both past and present building code provisions, subjected to a database of near-fault, pulse-like ground motions with varying pulse periods. Results show that the predicted collapse capacity is strongly influenced by variations in pulse period and building ductility; pulse periods that are longer than the first-mode elastic building period tend to be the most damaging. A detailed assessment of seismic collapse risk shows that the predicted probability of collapse in 50 years for modern concrete buildings at a representative near-fault site is approximately 6%, which is significantly higher than the 1% probability in the far-field region targeted by current seismic design maps in the US. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
5.
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
6.
当前国家对建筑结构的抗震性能和震后功能恢复能力提出了更高要求。基于短剪切型消能梁段的受剪屈服特性和剪切扩孔型螺栓连接的受剪滑移性能,提出一种新型扩孔螺栓连接型消能梁段,可有效增大消能梁段的延性和耗能能力并同时减小消能梁段的损伤,使带扩孔螺栓连接型消能梁段的新型Y形偏心支撑结构更好地适应当前要求。采用有限元方法详细分析扩孔螺栓连接型消能梁段的滞回性能、破坏模式和耗能机理,由此得到其骨架曲线和力学模型,并阐述其力学模型的影响参数,为相应偏心支撑结构的设计和分析提供理论依据。 相似文献
7.
以往通过专家经验判断遗址公园建筑结构地震安全性时存在一定误差,可信性低,因此提出新的遗址公园建筑结构的地震安全性鉴定方法。构建材料本构模型,判断遗址公园建筑结构损伤情况;使用局部损伤指数评价模型,计算遗址公园建筑结构局部损伤指数;通过局部损伤指数获取遗址公园建筑整体结构损伤指数,以此为依据判断遗址公园建筑结构地震安全性。以古罗马遗址公园建筑结构为例,进行地震安全性分析。结果显示,当地震波幅值达到800 gal时,该遗址公园建筑结构地震安全性最差,损坏程度为高度损坏,且此方法的分析结果精度极高,可信性强。 相似文献
8.
提出基于构件性能的混凝土高层建筑结构地震破坏抗毁能力评估方法,采用强度与延性法分析混凝土高层建筑构件强度和变形,以对强震作用下混凝土高层建筑结构性能实施准确描述。基于建筑结构性能以及多条地震波情况下高层建筑结构倒塌极限状态的分析规范,采用IDA方法设置建筑结构抗倒塌能力系数,并依据该系数获取基于构件性能的混凝土高层建筑结构地震破坏抗毁能力评估流程,实现建筑结构地震破坏抗毁能力的准确评估。实验结果说明,所提方法实现了混凝土高层建筑结构地震破坏抗毁能力的准确评估。 相似文献
9.
对3种不同厚度的钢材标准试件进行酸性大气环境气雾加速腐蚀试验,并对锈蚀后的试件进行单向拉伸试验,得到钢材力学性能随失重率的衰变规律。同时考虑构件截面削弱与材料力学性能降低,建立不同锈蚀程度下的钢框架有限元分析模型,利用非线性静力推覆分析得到锈蚀钢框架结构的整体初始刚度随锈蚀程度增大的退化规律,以表征结构因锈蚀造成的损伤。提出同时反映最大变形效应和累积耗能效应的双参数结构整体地震损伤模型,并在此损伤模型的基础上集合钢材材性试验结果及有限元分析结果,提出适用于锈蚀钢结构的"时变"损伤模型。对比分析以层间位移角及时变损伤模型为性能指标建立的不同龄期钢框架结构的地震易损性曲线,结果表明:随着锈蚀程度的增加,在相同地震动强度下结构超越某一极限状态的失效概率均增大。 相似文献
10.
Seismic design of concrete structures is currently based on time-invariant capacity design criteria which do not account for environmental hazards. The significant progressive decay of strength and ductility of concrete structures exposed to damage, in particular due to reinforcing steel corrosion, shows that this approach should be revised to consider the deterioration over time of the seismic performance. This is important also for precast systems, for which most of structural members are often directly exposed to the atmosphere and environmental aggressiveness. This paper presents a probabilistic approach for the lifetime assessment of seismic performance of concrete structures considering the interaction of seismic and environmental hazards. The effectiveness of the proposed approach is shown by its application to multistory precast buildings exposed to corrosion. The results show that structures designed for the same seismic action could have different lifetime seismic performance depending on the environmental exposure. These results emphasize the importance of a life-cycle approach to both seismic assessment of existing buildings and seismic design of new structures, and indicate that capacity design criteria need to be properly revised to consider the severity of the environmental exposure. 相似文献
11.
F. Braga V. Manfredi A. Masi A. Salvatori M. Vona 《Bulletin of Earthquake Engineering》2011,9(1):307-324
In Italy infills and partitions (non-structural elements) are typically made up of hollow brick masonry, disposed in one or
two parallel vertical walls. Many studies have analysed their role on the seismic behaviour of moment resisting framed RC
buildings and many seismic codes, all over the world, have provided specific additional measures for them. During the Abruzzo
seismic sequence, non-structural damage in RC buildings, both private and public, was extensive, varying from small cracks
to collapse, along with minor or no damage to structural elements. This damage involved a number of buildings, both old and
recently completed, determining heavy socio-economic consequences, including human casualties, loss of building functionality
(particularly important in case of strategic constructions), and unusable buildings. In this paper a review of the most frequent
damage patterns is performed, aimed at identifying the main causes of damage and linking them to commonly adopted construction
rules. For this purpose, local and global structural configurations frequently exhibiting non-structural damage are described,
aside from out-of-plane and in-plane failures. Furthermore, a review of code provisions on non structural elements has been
performed in the paper making reference to the most prominent current seismic codes and, finally, some design and construction
rules are suggested. 相似文献
12.
对4榀相同特性的砖墙进行不同程度的酸雨腐蚀试验及低周反复荷载试验,得出其在不同腐蚀循环次数下的滞回曲线。基于陆新征-曲哲恢复力模型对砖墙试件进行模拟分析,并与试验结果进行对比,验证得出三弹簧单元模型能够较准确预测砌体构件的滞回性能。利用三弹簧单元模型对不同腐蚀次数下砌体结构进行IDA分析,得出不同腐蚀次数下砌体结构的易损性曲线,通过对"小震"、"中震"、"大震"下结构失效概率的分析得出,酸雨腐蚀能够严重影响结构的力学性能,使得结构的抗震性能显著下降。 相似文献
13.
Performance-Based Seismic Design is now widely recognized as the pre-eminent seismic design and assessment methodology for
building structures. In recognition of this, seismic codes may require that buildings achieve multiple performance objectives
such as withstanding moderate, yet frequently occurring earthquakes with minimal structural and non-structural damage, while
withstanding severe, but rare earthquakes without collapse and loss of life. These objectives are presumed to be satisfied
by some codes if the force-based design procedures are followed. This paper investigates the efficacy of the Eurocode 8 force-based
design provisions with respect to RC frame building design and expected seismic performance. Four, eight, and 16-storey moment
frame buildings were designed and analyzed using the code modal response spectrum analysis provisions. Non-linear time-history
analyses were subsequently performed to determine the simulated seismic response of the structures and to validate the Eurocode
8 force-based designs. The results indicate the design of flexural members in medium-to-long period structures is not significantly
influenced by the choice of effective member stiffness; however, calculated interstorey drift demands are significantly affected.
This finding was primarily attributed to the code’s enforcement of a minimum spectral ordinate on the design spectrum. Furthermore,
design storey forces and interstorey drift demand estimates (and therefore damage), obtained by application of the code force-based
design procedure varied substantially from those found through non-linear time-history analysis. Overall, the results suggest
that though the Eurocode 8 may yield life-safe designs, the seismic performance of frame buildings of the same type and ductility
class can be highly non-uniform. 相似文献
14.
剪切型结构的抗震强度折减系数研究 总被引：1，自引：0，他引：1
为了研究剪切型结构抗震强度需求的变化规律,本文基于单自由度体系的非线性时程分析,研究了不同场地条件下延性折减系数与位移延性系数和结构自振周期的关系;采用修正等效单自由度体系位移延性折减系数的方法,研究了剪切型多自由度体系的延性折减系数;以基于中国建筑抗震规范设计的代表不同抗震能力要求的RC框架结构为分析对象,通过静力弹塑性分析,研究了RC框架结构的体系超强能力。分析结果表明场地类别、位移延性水准和结构振动周期对单自由度体系的延性折减系数有显著的影响;多自由度体系的抗震延性折减系数明显比其相应的等效单自由度体系的抗震延性折减系数小;RC框架结构的超强系数一般随结构楼层数的增加而减小,随抗震设防烈度的增大而减小,内框架的超强系数比边框架的超强系数大。 相似文献
15.
The study of the torsional response of buildings in the inelastic range of behaviour is of great interest since the ability of structures to resist strong earthquakes mainly relies on their ductility and capacity for energy dissipation. Furthermore, an examination of the performance of structures during past earthquakes demonstrates that plan-asymmetric buildings suffered greater damage due to torsional response. The paper deals with this subject by analysing a model which idealizes a one-storey building with resisting elements oriented along two perpendicular directions. In addition to the parameters of the elastic behaviour, the inelastic system response depends on full yield capacity and plan-wise strength distribution. The influence of the criterion adopted for the design of resisting elements on local ductility demand and damage has been evaluated by parametric analysis. In particular, a comparison has been carried out between systems with equal design levels for all elements and systems with design levels dependent on the element location. For a given elastic behaviour and total capacity, the strength distributions in plan have been defined which minimize ductility demand and structural damage. Finally, based on these findings, responses from models designed according to several seismic codes have been compared. 相似文献
16.
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。 相似文献
17.
18.
Past earthquake experiences indicate that most buildings designed in accordance with modern seismic design codes could survive moderate‐to‐strong earthquakes; however, the financial loss due to repairing cost and the subsequent business interruption can be unacceptable. Designing building structures to meet desired performance targets has become a clear direction in future seismic design practice. As a matter of fact, the performance of buildings is affected by structural as well as non‐structural components, and involves numerous uncertainties. Therefore, appropriate probabilistic approach taking into account structural and non‐structural damages is required. This paper presents a fuzzy–random model for the performance reliability analysis of RC framed structures considering both structural and non‐structural damages. The limit state for each performance level is defined as an interval of inter‐storey drift ratios concerning, respectively, the non‐structural and structural damage with a membership function, while the relative importance of the two aspects is reflected through the use of an appropriate cost function. To illustrate the methodology, herein the non‐structural damage is represented by infill masonry walls. The probabilistic drift limits for RC components and masonry walls from the associated studies are employed to facilitate the demonstration of the proposed model in an example case study. The results are compared with those obtained using classical reliability model based on single‐threshold performance definition. The proposed model provides a good basis for incorporating different aspects into the performance assessment of a building system. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
19.
Worldwide experience repeatedly shows that damages in structures caused by earthquakes are highly dependent on site condition and epicentral distance. In this paper, a 21-storey shear wall-structure built in the 1960s in Hong Kong is selected as an example to investigate these two effects. Under various design earthquake intensities and for various site conditions, the fragility curves or damage probability matrix of such building is quantified in terms of the ductility factor, which is estimated from the ratio of storey yield shear to the inter-storey seismic shear. For high-rise buildings, a higher probability of damage is obtained for a softer site condition, and damage is more severe for far field earthquakes than for near field earthquakes. For earthquake intensity of VIII, the probability of complete collapse (P) increases from 1 to 24% for near field earthquakes and from 1 to 41% for far field earthquakes if the building is moved form a rock site to a site consisting a 80 m thick soft clay. For intensity IX, P increases from 6 to 69% for near field earthquake and from 14 to 79% for far field earthquake if the building is again moved form rock site to soft soil site. Therefore, site effect is very important and not to be neglected. Similar site and epicentral effects should also be expected for other types of high-rise structures. 相似文献
20.
A multi‐level seismic vulnerability assessment of reinforced concrete moment frame buildings located in moderate seismic zones (0.25g) is performed on a set of ductile versions of low‐ to mid‐rise two‐dimensional moment frames. The study is illustrated through application to comparative trial designs of two (4‐ and 8‐story) buildings adopting both space‐ and perimeter‐framed approaches. All frames are dimensioned as per the emerging version of the seismic design code in Egypt. These new seismic provisions are in line with current European norms for seismic design of buildings. Code‐compliant designs (CCD), as well as a proposed modified code design relaxing design drift demands for the investigated buildings, are examined to test their effectiveness and reliability. Applying nonlinear inelastic incremental dynamic analyses, fragility curves (FC) for the frames are developed corresponding to various code‐specified performance levels. Code preset lower and upper bounds on design acceleration and drift, respectively, are also addressed along with their implications, if imposed, on the frames seismic performance and vulnerability. Annual spectral acceleration hazard curves for the case study frames are also generated. Estimates for mean annual frequency (MAF) of exceeding various performance levels are then computed through an integration process of the data resulting from the FC with the site hazard curves. The study demonstrates that the proposed design procedure relaxing design drift demands delivers more economic building designs relative to CCDs, yet without risking the global safety of the structure. The relaxed design technique suggested herein, even though scoring higher, as expected by intuition, MAF of exceeding various code‐limiting performance levels expressed in terms of interstory drift ratios, still guarantees a reasonably acceptable actual margin against violating code limits for such levels. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献