共查询到20条相似文献，搜索用时 500 毫秒
1.
《地震工程与工程振动(英文版)》2021,20(3)
This paper provides a general perspective of the seismic performance of a nature-inspired, honey-comb grid structural system, known as a hexagrid, under near-field ground motions. Seismic performance of this skeleton is then compared to that of a bundled-tube, as a conventional and efficient load-resisting system in order to provide a better perception of the seismic behavior of a hexagrid skeleton. Two 20-story buildings with bundled-tube and hexagrid skeleton were studied. Nonlinear behavior of the structures was investigated through 3-D finite element computer models and nonlinear time history analyses by subjecting the models to seven three-component records of scaled near-field ground motions. Distribution of peak inter story drift and corner beam-column joint rotations were calculated and compared. Results indicated that by replacing the exterior columns of the bundled-tube system with inclined beam-column elements of nature-inspired hexagons, lateral stiffness of the building increased and it would tolerate less deformations before global dynamic instability is reached. The presence of inclined columns in the hexagrid skeleton helped to concentrate local nonlinearities in ring beams rather than exterior columns. 相似文献
2.
Modified consecutive modal pushover procedure for seismic investigation of one-way asymmetric-plan tall buildings 总被引：1，自引：1，他引：0
The effects of higher modes and torsion have a significant impact on the seismic responses of asymmetric-plan tall buildings.A consecutive modal pushover(CMP) procedure is one of the pushover methods that have been developed to consider these effects.The aim of this paper is to modify the(CMP) analysis procedure to estimate the seismic demands of one-way asymmetric-plan tall buildings with dual systems.An analysis of 10-,15-and 20-story asymmetric-plan buildings is carried out,and the results from the modified consecutive modal pushover(MCMP) procedure are compared with those obtained from the modal pushover analysis(MPA) procedure and the nonlinear time history analysis(NLTHA).The MCMP estimates of the seismic demands of one-way asymmetric-plan buildings demonstrate a reasonable accuracy,compared to the results obtained from the NLTHA.Furthermore,the accuracy of the MCMP procedure in the prediction of plastic hinge rotations is better than the MPA procedure.The new pushover procedure is also more accurate than the FEMA load distribution and the MPA procedure. 相似文献
3.
Loss estimation for non‐ductile reinforced concrete building in Victoria,British Columbia,Canada: effects of mega‐thrust Mw9‐class subduction earthquakes and aftershocks 
下载免费PDF全文
下载免费PDF全文 This paper presents, within the performance‐based earthquake engineering framework, a comprehensive probabilistic seismic loss estimation method that accounts for main sources of uncertainty related to hazard, vulnerability, and loss. The loss assessment rigorously integrates multiple engineering demand parameters (maximum and residual inter‐story drift ratio and peak floor acceleration) with consideration of mainshock–aftershock sequences. A 4‐story non‐ductile reinforced concrete building located in Victoria, British Colombia, Canada, is considered as a case study. For 100 mainshock and mainshock–aftershock earthquake records, incremental dynamic analysis is performed, and the three engineering demand parameters are fitted with a probability distribution and corresponding dependence computed. Finally, with consideration of different demolition limit states, loss assessment is performed. From the results, it can be shown that when seismic vulnerability models are integrated with seismic hazard, the aftershock effects are relatively minor in terms of overall seismic loss (1–4% increase). Moreover, demolition limit state parameters, uncertainties of collapse fragility, and non‐collapse seismic demand prediction models have showed significant contribution to the loss assessment. The seismic loss curves for the reference case and for cases with the varied parameters can differ by as large as about 150%. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
4.
Linear elastic analysis procedures are employed exclusively in the traditional seismic design of new structures and widely employed in the seismic assessment of existing structures. It is also a convenient tool for the initial checking of deformations in displacement‐based design. The limitations that should be imposed on linear elastic procedures have been evaluated in this study by comparing the deformation‐based response quantities obtained from response spectrum analysis with those from the nonlinear time history analysis. Both procedures were applied to different design variants of 5, 8, and 12 story moment frames, subjected to 20 strong motion components exhibiting a variety of intensities. Member plastic rotations and interstory drift ratios were employed as the basic response parameter in performance assessment. It has been found that average column demand to capacity ratio (DCR) (the ratio of flexural demand from linear elastic analysis to flexural capacity) and average beam DCR at the critical story are the most effective parameters in determining the validity range of linear elastic procedures in regular moment frames. Limiting values for these response parameters are proposed. Furthermore, amplification factors for member rotation demands predicted by the linear procedures are suggested for moment frames when these limiting values are exceeded. These factors ensure that the amplified linear elastic rotations are not smaller than 84 percentile (mean – 1sigma) of the rotations obtained from nonlinear time history analysis. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
强震发生后通常伴随着余震,余震的发生会加重结构损伤甚至引发倒塌。为了量化研究主余震序列型地震动对结构损伤的影响,以一栋3层钢筋混凝土框架结构为研究对象,选取了10条实际的主余震记录作为地震动输入,采用ABAQUS非线性有限元软件对该框架结构进行非线性动力时程分析,并依据结构局部和整体损伤耗能指标来评价主余震序列型地震动对框架结构累积损伤的影响。研究结果表明:序列地震会加剧结构底层柱的局部损伤耗能,特别是对底层中柱的影响更加明显;序列地震作用下的结构整体损伤耗能平均值相对于单主震作用下增加约30%;当余震与主震的第一周期谱加速度指标的比值Sa （T1）余震/Sa （T1）主震较大时,序列地震对结构损伤需求的影响更为显著。 相似文献
6.
This paper introduces and evaluates a methodology for the aftershock seismic assessment of buildings taking explicitly into account residual drift demands after the mainshock (i.e., postmainshock residual interstory drifts, RIDRo). The methodology is applied to a testbed four‐story steel moment‐resisting building designed with modern seismic design provisions when subjected to a set of near‐fault mainshock–aftershock seismic sequences that induce five levels of RIDRo. Once the postmainshock residual drift is induced to the building model, a postmainshock incremental dynamic analysis is performed under each aftershock to obtain its collapse capacity and its capacity associated to demolition (i.e., the capacity to reach or exceed a 2% residual drift). The effect of additional sources of stiffness and strength (i.e., interior gravity frames and slab contribution) and the polarity of the aftershocks are examined in this study. Results of this investigation show that the collapse potential under aftershocks strongly depends on the modeling approach (i.e., the aftershock collapse potential is modified when additional sources of lateral stiffness and strength are included in the analytical model). Furthermore, it is demonstrated that the aftershock capacity associated to demolition (i.e., the aftershock collapse capacity associated to a residual interstory drift that leads to an imminent demolition) is lower than that of the aftershock collapse capacity, which mean that this parameter should be a better measure of the building residual capacity against aftershocks. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
结构在主震作用下发生损伤,由于刚度和强度退化导致结构周期的延长,再加上高阶周期的影响,在随后的余震对主震损伤结构抗震性能的影响分析中,基于弹性周期的传统谱加速度可能不适用,有必要对地震动强度指标的选择进行进一步研究。本文以9层Benchmark钢框架为研究对象,选取10种地震动强度指标,分别从离散性和相关性两个维度对比分析了其在余震IDA分析中的优劣性。研究结果表明:与最大层间位移角相比,最大残余层间位移角更能够准确地量化主震对结构造成的损伤;对于钢框架结构,基于一段周期的几何平均谱加速度的IMBoj&Lev指标是最优的地震动强度指标,相对于Sa（T1）离散性降低了30%左右,相关性提高了6%左右。 相似文献
8.
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
9.
研究我国东部9次余震序列的总体特征得到:余震频度符合 n=n1t-h关系;频度和强度随时间衰减较慢;最大地震后3、4天内发生的余震所勾划的余震区常常比最终余震区小;多数余震分布在地壳中5至10公里的深度上.一些强余震前的中小余震时空分布有下述特征:（1）强余震前几天至十几天,余震序列的频度偏离正常衰减值;（2）强余震前有中小余震震中向下一次强余震的震中附近扩展或形成空区的现象;（3）强余震前震级序列出现缺震现象;（4）余震序列有准周期性.上述特性预示其后将发生强余震,同时表明强余震有类似于大地震的孕震过程.种种现象还表明余震序列在时间和空间上可能是由主震的直接余震和强余震的次级余震相互叠加所组成的.最后将某些特性和岩石试验结果进行了比较和讨论. 相似文献
10.
Aftershocks have been shown to exacerbate earthquake‐induced financial losses by causing further damage to structural and nonstructural components in buildings that have already been affected by a mainshock event and increasing the duration of disrupted functionality. Whereas seismic loss assessment under isolated events has been addressed thoroughly in previous studies, comparatively less has been accomplished in the area of loss assessment under sequences of mainshock‐aftershock ground motions. The main objective of the current study is to formulate a comprehensive framework for quantifying financial losses under sequential seismic events. The proposed framework is capable of accounting for the uncertainties in the state of structure due to accumulation of earthquake‐induced damage, the time‐dependent nature of seismic hazard in the post‐mainshock environment, and the uncertainties in the occurrence of mainshock and aftershock events. Application of the proposed framework to a 4‐story reinforced concrete moment frame shows that consideration of aftershocks could increase lifecycle earthquake‐induced losses by up to 30% compared with mainshock‐only assessments. 相似文献
11.
层间隔震结构作为一种新型的隔震形式,不仅可以降低上部结构的动力响应,还可以弥补基础隔震结构的不足.现有研究多集中在远场地震作用下的规则层间隔震结构.本文利用通用结构分析与设计软件SAP2000分别模拟了一幢8层带裙房钢筋混凝土框架层间隔震结构、基础隔震结构和抗震结构,分析并对比了三种结构在近场地震作用下动力响应特征.结果表明在近场条件下三种结构顶层均出现不同程度的鞭梢效应;相比抗震结构两种隔震结构具有很好的减震效果,而且基础隔震结构的减震效果好于层间隔震结构;由于结构刚度突变的部位剪力较大,所以应对其裙楼顶部予以加强. 相似文献
12.
A large mainshock may trigger numerous aftershocks within a short period, and nuclear power plant (NPP) structures have the probability to be exposed to mainshock–aftershock seismic sequences. However, the researchers focused on seismic analyses of reinforced concrete containment (RCC) buildings under only mainshocks. The aim of this paper is to thoroughly investigate the dynamic responses of a RCC building under mainshock–aftershock seismic sequences. For that purpose, 10 as-recorded mainshock–aftershock seismic sequences with two horizontal components are considered in this study, and a typical three-dimensional RCC model subjected to the selected as-recorded seismic sequences is established. Peak ground accelerations (PGAs) of mainshocks equal to 0.3 g (safe shutdown earthquake load-SSE load) are considered in this paper. The results indicate that aftershocks have a significant effect on the responses of the RCC in terms of maximum top accelerations, maximum top displacements and accumulated damage. Furthermore, in order to preserve the RCC from large damage under repeated earthquakes, local damage and global damage indices are suggested as limitations under only mainshocks. 相似文献
13.
The drift pushover analysis method for tall and regular buildings is extended in this paper to the third dimension. The focus of study is on the structures with important torsional response. For this purpose, 10, 15, 20 and 30-story steel moment frame buildings having unsymmetrical plans with 5–30% eccentricity ratios are studied. For evaluation of accuracy, nonlinear dynamic response of the buildings is determined under a consistent suit of earthquake ground motions. The maxima of the story drifts and shears and cumulative plastic hinge rotations of stories are calculated under the ground motions and their averages along with those of the modal pushover procedure are compared with the results of the presented method. The comparative analysis establishes the good accuracy of the three dimensional drift pushover method. 相似文献
14.
RC buildings retrofitted by converting frame bays into RC walls 总被引：1，自引：1，他引：0
Michael N. Fardis Antonis Schetakis Elias Strepelias 《Bulletin of Earthquake Engineering》2013,11(5):1541-1561
Adding concrete walls by infilling certain frame bays with reinforced concrete is popular for seismic retrofitting, but is covered by codes only if the connection of the old concrete to the new ensures monolithic behavior. To avoid penalizing the foundation of the new wall with a very high moment resistance, the new concrete should not be thicker than, or surround, the old frame members. A cost-effective connection of these members to a thin new web is proposed, alongside a design procedure and detailing that conform to current codes. Owing to practical difficulties, footings of added walls are often small and weakly connected to the other footings, hence they uplift and rock during the earthquake. The model for uplift of 3D footings consists of two pairs of nonlinear-elastic springs in a cross layout and approximates also moderate nonlinearities in the soil continuum. It is used in nonlinear, static or dynamic, analyses of three buildings with added walls. The analyses of a clean, regular 4-story building show the benefit from uplift to the added walls and a certain adverse effect on some columns but not on beams, as well as the lack of a clear positive effect of tie-beams. The application to a 7-story and a 2-story real building with extreme, yet typical, irregularities in plan and elevation exemplifies the real-life restrictions in the use of added walls and shows their limits for the improvement of seismic performance; certain deficiencies in flexure or shear remain in both and are corrected at very low cost with local fiber reinforced polymer (FRP) jackets without new analysis of the building, as FRPs do not change the member effective stiffness or moment resistance. 相似文献
15.
碳纤维布增强混凝土框架抗震性能的有限元分析 总被引：2，自引：1，他引：1
利用碳纤维布（CFS）对一个9层钢筋混凝土框架的底层柱进行了加固,运用有限元程序对加固前后结构的整体抗震性能进行了动力分析.分析结果表明,利用碳纤维布加固底部框架柱有助于提高框架的整体抗震性能,从而减少框架在地震作用下的最大侧移和各层间位移. 相似文献
16.
Hossein Ebrahimian Fatemeh Jalayer Domenico Asprone Anna M. Lombardi Warner Marzocchi Andrea Prota Gaetano Manfredi 《地震工程与结构动力学》2014,43(14):2179-2197
Operative seismic aftershock risk forecasting can be particularly useful for rapid decision‐making in the presence of an ongoing sequence. In such a context, limit state first‐excursion probabilities (risk) for the forecasting interval (a day) can represent the potential for progressive state of damage in a structure. This work lays out a performance‐based framework for adaptive aftershock risk assessment in the immediate post‐mainshock environment. A time‐dependent structural performance variable is adopted in order to measure the cumulative damage in a structure. A set of event‐dependent fragility curves as a function of the first‐mode spectral acceleration for a prescribed limit state is calculated by employing back‐to‐back nonlinear dynamic analyses. An epidemic‐type aftershock sequence model is employed for estimating the spatio‐temporal evolution of aftershocks. The event‐dependent fragility curves for a given limit state are then integrated together with the probability distribution of aftershock spectral acceleration based on the epidemic‐type aftershock sequence aftershock hazard. The daily probability of limit state first‐excursion is finally calculated as a weighted combination of the sequence of limit state probabilities conditioned on the number of aftershocks. As a numerical example, daily aftershock risk is calculated for the L'Aquila 2009 aftershock sequence (central Italy). A representative three‐story reinforced concrete frame with infill panels, which has cyclic strength and stiffness degradation, is used in order to evaluate the progressive damage. It is observed that the proposed framework leads to a sound forecasting of limit state first‐excursion in the structure for two limit states of significant damage and near collapse. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
17.
This paper presents a new procedure to transform an SSI system into an equivalent SDOF system using twice equivalence. A pushover analysis procedure based on the capacity spectrum method for buildings with SSI effects （PASSI） is then established based on the equivalent SDOF system, and the modified response spectrum and equivalent capacity spectrum are obtained. Furthermore, the approximate formulas to obtain the dynamic stiffness of foundations are suggested. Three steel buildings with different story heights （3, 9 and 20） including SSI effects are analyzed under two far-field and two near-field historical records and an artificial seismic time history using the two PASSI procedures and the nonlinear response history analysis （NLhRHA） method. The results are compared and discussed. Finally, combined with seismic design response spectrum, the nonlinear seismic response of a 9-story building with SSI effects is analyzed using the PASSI procedures, and its seismic performance is evaluated according to the Chinese ＇Code for Seismic Design of Buildings. The feasibility of the proposed procedure is verified. 相似文献
18.
This paper presents an experimental investigation on semi-active seismic response control of a multistory building with a podium structure using multiple magnetorheological (MR) dampers manipulated by a logic control algorithm. The experiments are performed in three phases on a seismic simulator with a slender 12-story building model representing a multi-story building and a relatively stiff 3-story building model typifying a podium structure. The first phase of the investigation is to assess control performance of using three MR dampers to link the 3-story building to the 12-story building, in which seismic responses of the controlled two buildings are compared with those of the two buildings without any connection and with rigid connection. The second phase is to investigate reliability of the semi-active control system and robustness of the logic control algorithm when 2 out of 3 MR dampers fail and when the electricity supply to MR dampers is completely stopped. The last phase is to examine sensitivity of semi-active control performance of two buildings to change in ground excitation. The experimental results show that multiple MR dampers with the logic control algorithm can achieve a significant reduction in seismic responses of both buildings. The proposed semi-active control system is of high reliability and good robustness. 相似文献
19.
The present study focuses on the influence of repeated earthquakes on the maximum story ductility demands of three-dimensional inelastic concrete frames. A comprehensive assessment is conducted using generic frames with 3-, 6-, 12-, and 18-story structures. Each is assumed to have behaviour factors of 1.5, 2, 4, and 6 referring to Eurocode 8. Stiffness and strength degrading hysteresis rule to represent reinforced concrete structure is considered in the plastic hinge of members. Twenty ground motions are selected, and single, double, and triple events of synthetic repeated earthquakes are considered. Some interesting findings are provided showing that repeated earthquakes significantly increase the story ductility demand of inelastic concrete frames. On average, relative increment of maximum story ductility demand is experienced 1.4 and 1.3 times when double and triple events of repeated earthquakes are induced, respectively. Empirical relationships are also provided to predict these increments where their efficiency is presented examining characteristic 3- and 8-story reinforced concrete buildings. 相似文献
20.
Evaluation of displacement coefficient method for seismically retrofitted buildings with various ductility capacities 下载免费PDF全文
下载免费PDF全文 This research study is aimed at evaluating the accuracy of the displacement coefficient method (DCM) of FEMA 440 and associated nonlinear static procedure (NLSP) for actual buildings with soft story mechanism and various ductility capacities. The DCM and associated NLSP are evaluated using two existing seismically vulnerable buildings with soft story mechanism. The buildings are first retrofitted using a ductile steel‐brace‐link system to represent those with good ductility capacity and then retrofitted with RC squat infill shear panels (SISPs) to represent those with relatively poor ductility capacity. The evaluation of the DCM of FEMA 440 and associated NLSP is then performed by comparing the roof displacements (target displacements), maximum interstory drifts, and maximum plastic hinge rotations of the original and retrofitted buildings obtained from NLSP (at the target displacement level of DCM) with those obtained from nonlinear response history (NRH) analyses for three different seismic performance levels. It is observed that the DCM, and hence, the NLSP fail to accurately predict the NRH analyses results mainly due to uncertainties in the coefficient C1 of the DCM in the short period range, the inability of the DCM to capture the failure of structural members beyond a certain lateral displacement or plastic rotation limit and associated soft story mechanism. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献