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组合基础隔震结构双向地震反应分析 总被引：2，自引：0，他引：2
本文采用双向耦合恢复力模型模拟组合隔震系统中隔震支座的双向耦合效应,对组合基础隔震结构进行了单向和双向地震反应对比分析,分析表明在水平双向地震作用下结构各层的加速度反应较小,隔震层的层间位移较大,而上部结构的层间位移较小,并且在水平双向地震作用下,支座的最大位移明显大于单向地震作用时支座的最大位移,因而应考虑水平双向地震作用对组合基础隔震结构地震反应和隔震支座性能的影响。 相似文献
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Petros Komodromos Panayiotis C. Polycarpou Loizos Papaloizou Marios C. Phocas 《地震工程与结构动力学》2007,36(12):1605-1622
Numerical simulations and parametric studies have been used to investigate the influence of potential poundings of seismically isolated buildings with adjacent structures on the effectiveness of seismic isolation. Poundings are assumed to occur at the isolation level between the seismically isolated building and the surrounding moat wall. After assessing some common force‐based impact models, a variation of the linear viscoelastic impact model is proposed to avoid tensile impact forces during detachment, while enabling the consideration of permanent plastic deformations at the vicinity of the impact. A large number of numerical simulations of seismically isolated buildings with different characteristics have been conducted under six earthquake excitations in order to investigate the influence of various design parameters and conditions on the peak floor accelerations and interstorey deflections during poundings. The numerical simulations demonstrate that poundings may substantially increase floor accelerations, especially t the base floor where impacts occur. Higher modes of vibration are excided during poundings, increasing the interstorey deflections, instead of retaining an almost rigid‐body motion of the superstructure, which is aimed with seismic isolation. Impact stiffness seems to affect significantly the acceleration response at the isolation level, while the displacement response is more insensitive to the variation of the impact stiffness. Finally, the results indicate that providing excessive flexibility at the isolation system to minimize the floor accelerations may lead to a building vulnerable to poundings, if the available seismic gap is limited. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Shear building representations of seismically isolated buildings 总被引：2，自引：0，他引：2
Seismic isolation, with its capability of reducing floor accelerations and interstory drifts simultaneously, is recognized
as an earthquake resistant design method that protects contents of a building along with the building itself. In research
studies, superstructures of seismically isolated buildings are commonly modeled as idealized shear buildings. Shear building
representation corresponds to an idealized structure where the beams are infinitely stiff in flexure and axially inextensible;
columns are axially inextensible; and rigid floors are supported on these columns. Although it is more convenient to model
and analyze a shear building, such an idealization may influence the seismic responses of seismically isolated buildings.
This study presents a comparison of the seismic performances of seismically isolated buildings with superstructures modeled
as shear buildings to those with full three dimensional superstructures. Both linear and nonlinear base isolation systems
with different isolation periods and superstructures with different number of stories are considered. 相似文献
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Structural performance of a base-isolated reinforced concrete building subjected to seismic pounding
The effects of seismic pounding on the structural performance of a base-isolated reinforced concrete (RC) building are investigated, with a view to evaluate the influence of adjacent structures and separation between structures on the pounding response. In particular, seismic pounding of a typical four-story base-isolated RC building with retaining walls at the base and with a four-story fixed-base RC building is studied. Three-dimensional finite element analyses are carried out considering material and geometric nonlinearities. The structural performance of the base-isolated building is evaluated considering various earthquake excitations. It is found that the performance of the base-isolated building is substantially influenced by the pounding. The investigated base-isolated building shows good resistance against shear failure and the predominant mode of failure due to pounding is flexural. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Many closely located adjacent buildings have suffered from pounding during past earthquakes because they vibrated out of phase.Furthermore,buildings are usually constructed on soil;hence,there are interactions between the buildings and the underlying soil that should also be considered.This paper examines both the interaction between adjacent buildings due to pounding and the interaction between the buildings through the soil as they affect the buildings’ seismic responses.The developed model consists of adjacent shear buildings resting on a discrete soil model and a linear viscoelastic contact force model that connects the buildings during pounding.The seismic responses of adjacent buildings due to ground accelerations are obtained for two conditions:fixed-based(FB) and structure-soil-structure interaction(SSSI).The results indicate that pounding worsens the buildings’ condition because their seismic responses are amplified after pounding.Moreover,the underlying soil negatively impacts the buildings’ seismic responses during pounding because the ratio of their seismic response under SSSI conditions with pounding to those without pounding is greater than that of the FB condition. 相似文献
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The use of collision shear walls (bumper‐type), acting transversely to the side subject to pounding, as a measure to minimize damage of reinforced concrete buildings in contact, is investigated using 5‐story building models. The buildings were designed according to the Greek anti‐seismic and reinforced concrete design codes. Owing to story height differences potential pounding in case of an earthquake will occur between floor slabs, a case specifically chosen because this is when pounding can turn out to be catastrophic. The investigation is carried out using nonlinear dynamic analyses for a real earthquake motion and also a simplified solution for a triangular dynamic force of short duration, comparable to the forces caused by pounding. For such analyses, nonlinear, prismatic beam–column elements are used and the effects of pounding are expressed in terms of changes in rotational ductility factors of the building elements. The local effects of pounding on the collision shear walls are investigated using a detailed nonlinear finite element model of the shear walls and results are expressed in terms of induced stresses. It is found that pounding will cause instantaneous acceleration pulses in the colliding buildings and will somewhat increase ductility demands in the members of the top floor, but all within tolerable limits. At the same time the collision walls will suffer repairable local damage at the points of contact, but will effectively protect both buildings from collapse, which could occur if columns were in the place of the walls. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Base‐isolated buildings are typically important facilities expected to remain functional after a major earthquake. However, their behavior under extreme ground shaking is not well understood. A series of earthquake simulator experiments were performed to assess performance limit states of seismically isolated buildings under strong ground motions, including pounding against a moat wall. The test setup consists of a quarter scale three‐story frame isolated at the base with friction pendulum bearings and a moat wall model. An effort was made to properly scale the strength and the stiffness of the frame relative to the bearings properties from a professionally designed isolated three‐story steel intermediate moment‐resisting frame so that realistic yielding mechanisms can be observed. The moat wall was modeled as either a rigid triangle steel stopper or a concrete wall of various thicknesses with soil backfill. The moat wall gap was set to various displacement increments to examine the sensitivity of this parameter and also to assess the effects of impact on the superstructure at different velocities. The test results indicate that the contact forces are largely dependent on the gap distance, impact velocity and wall flexibility and, in extreme cases, pounding can induce yielding in the superstructure. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Post‐tensioned (PT) self‐centering moment‐resisting frames (MRFs) have recently been developed as an alternative to welded moment frames. The first generation of these systems incorporated yielding energy dissipation mechanisms, whereas more recently, PT self‐centering friction damped (SCFR) moment‐resistant connections have been proposed and experimentally validated. Although all of these systems exhibited good stiffness, strength and ductility properties and stable dissipation of energy under cyclic loading, questions concerning their ultimate response still remained and a complete design methodology to allow engineers to conceive structures using these systems was also needed. In this paper, the mechanics of SCFR frames are first described and a comprehensive design procedure that accounts for the frame behavior and the nonlinear dynamics of self‐centering frames is then elaborated. A strategy for the response of these systems at ultimate deformation stages is then proposed and detailing requirements on the beams in order to achieve this response are outlined. The proposed procedure aims to achieve designs where the interstory drifts for SCFR frames are similar to those of special steel welded moment‐resisting frames (WMRFs). Furthermore, this procedure is adapted from current seismic design practices and can be extended to any other PT self‐centering steel frame system. A six‐story building incorporating WMRFs was designed and a similar building incorporating SCFR frames were re‐designed by the proposed seismic design procedure. Time‐history analyses showed that the maximum interstory drifts and maximum floor accelerations of the SCFR frame were similar to those of the WMRF but that almost zero residual drifts were observed for the SCFR frame. The results obtained from the analyses confirmed the validity of the proposed seismic design procedure, since the peak drift values were similar to those prescribed by the seismic design codes and the SCFR frames achieved the intended performance level under both design and maximum considerable levels of seismic loading. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Brendon A. Bradley Rajesh P. Dhakal Gregory A. MacRae Misko Cubrinovski 《地震工程与结构动力学》2010,39(5):501-520
The efficacy of various ground motion intensity measures (IMs) in the prediction of spatially distributed seismic demands (engineering demand parameters, (EDPs)) within a structure is investigated. This has direct implications to building‐specific seismic loss estimation, where the seismic demand on different components is dependent on the location of the component in the structure. Several common IMs are investigated in terms of their ability to predict the spatially distributed demands in a 10‐storey office building, which is measured in terms of maximum interstorey drift ratios and maximum floor accelerations. It is found that the ability of an IM to efficiently predict a specific EDP depends on the similarity between the frequency range of the ground motion that controls the IM and that of the EDP. An IMs predictability has a direct effect on the median response demands for ground motions scaled to a specified probability of exceedance from a ground motion hazard curve. All of the IMs investigated were found to be insufficient with respect to at least one of magnitude, source‐to‐site distance, or epsilon when predicting all peak interstorey drifts and peak floor accelerations in a 10‐storey reinforced concrete frame structure. Careful ground motion selection and/or seismic demand modification is therefore required to predict such a spatially distributed demands without significant bias. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Shehata E. Abdel Raheem 《Bulletin of Earthquake Engineering》2014,12(4):1705-1724
Post-earthquake damages investigation in past and recent earthquakes has illustrated that the building structures are vulnerable to severe damage and/or collapse during moderate to strong ground motion. Among the possible structural damages, seismic induced pounding has been commonly observed in several earthquakes. A parametric study on buildings pounding response as well as proper seismic hazard mitigation practice for adjacent buildings is carried out. Three categories of recorded earthquake excitation are used for input excitations. The effect of impact is studied using linear and nonlinear contact force model for different separation distances and compared with nominal model without pounding consideration. The severity of the impact depends on the dynamic characteristics of the adjacent buildings in combination with the earthquake characteristics. Pounding produces acceleration and shear forces/stresses at various story levels that are greater than those obtained from the no pounding case, while the peak drift depends on the input excitation characteristics. Also, increasing gap width is likely to be effective when the separation is sufficiently wide to eliminate contact. Furthermore, it is effective to provide a shock absorber device system for the mitigation of impact effects between adjacent buildings with relatively narrow seismic gaps, where the sudden changes of stiffness during poundings can be smoothed. This prevents, to some extent, the acceleration peaks due to impact. The pounding forces exerted on the adjacent buildings can be satisfactorily reduced. 相似文献
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Conditional spectrum‐based ground motion record selection using average spectral acceleration 
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下载免费PDF全文 Mohsen Kohrangi Paolo Bazzurro Dimitrios Vamvatsikos Andrea Spillatura 《地震工程与结构动力学》2017,46(10):1667-1685
The use of a seismic intensity measure (IM) is paramount in decoupling seismic hazard and structural response estimation when assessing the performance of structures. For this to be valid, the IM needs to be sufficient;that is, the engineering demand parameter (EDP) response should be independent of other ground motion characteristics when conditioned on the IM. Whenever non‐trivial dependence is found, such as in the case of the IM being the first‐mode spectral acceleration, ground motion selection must be employed to generate sets of ground motion records that are consistent vis‐à‐vis the hazard conditioned on the IM. Conditional spectrum record selection is such a method for choosing records that are consistent with the site‐dependent spectral shape conditioned on the first‐mode spectral acceleration. Based on a single structural period, however the result may be suboptimal, or insufficient, for EDPs influenced by different period values, for example, peak interstory drifts or peak floor accelerations at different floors, potentially requiring different record suites for each. Recently, the log‐average spectral acceleration over a period range, AvgSA, has emerged as an improved scalar IM for building response estimation whose hazard can be evaluated using existing ground motion prediction equations. Herein, we present a recasting of conditional spectrum record selection that is based on AvgSA over a period range as the conditioning IM. This procedure ensures increased efficiency and sufficiency in simultaneously estimating multiple EDPs by means of a single IM. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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安装粘滞阻尼器结构的抗震设计方法研究 总被引：11，自引：1，他引：10
本文研究了安装粘滞阻尼器结构在常遇地震作用下层间最大剪力的分配情况,建立了层间最大构件力与层间最大剪力的关系以及层间最大附加力与层间最大剪力的关系,提出了该类结构在罕遇地震作用下层间弹塑性变形的简化计算方法,最后建议了安装滞阻尼器结构的抗震设计步骤。 相似文献
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为研究近断层地震动对曲线连续梁桥地震响应及碰撞效应的影响,采用非线性时程分析法,分别研究脉冲效应、上盘效应及方向性效应对某三跨曲线连续梁桥支座位移、桥墩内力及邻梁间碰撞力的影响;通过支座隔震率的对比分析,探究不同类型近断层地震动下地震响应产生差异的原因。研究结果表明:脉冲效应、上盘效应和方向性效应均会增大曲线连续梁桥地震响应,脉冲效应的影响尤为显著;脉冲效应和方向性效应削弱了高阻尼橡胶支座的隔震特性,而上盘效应对桥梁响应的影响仅与上盘地震动自身特性有关;综合来看,脉冲效应对曲线梁碰撞响应影响最明显,上盘效应影响不大。 相似文献
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Zhi Zhang Robert B. Fleischman Jose I. Restrepo Gabriele Guerrini Arpit Nema Dichuan Zhang Ulina Shakya Georgios Tsampras Richard Sause 《地震工程与结构动力学》2018,47(10):1987-2011
A new floor connecting system developed for low‐damage seismic‐resistant building structures is described herein. The system, termed Inertial Force‐Limiting Floor Anchorage System (IFAS), is intended to limit the lateral forces in buildings during an earthquake. This objective is accomplished by providing limited‐strength deformable connections between the floor system and the primary elements of the lateral force‐resisting system. The connections transform the seismic demands from inertial forces into relative displacements between the floors and lateral force‐resisting system. This paper presents the IFAS performance in a shake‐table testing program that provides a direct comparison with an equivalent conventional rigidly anchored‐floor structure. The test structure is a half‐scale, 4‐story reinforced concrete flat‐plate shear wall structure. Precast hybrid rocking walls and special precast columns were used for test repeatability in a 22‐input strong ground‐motion sequence. The structure was purposely designed with an eccentric wall layout to examine the performance of the system in coupled translational‐torsional response. The test results indicated a seismic demand reduction in the lateral force‐resisting system of the IFAS structure relative to the conventional structure, including reduced shear wall base rotation, shear wall and column inter‐story drift, and, in some cases, floor accelerations. These results indicate the potential for the IFAS to minimize damage to the primary structural and non‐structural components during earthquakes. 相似文献
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The seismic demand parameters including the floor acceleration amplification (FAA) factors and the interstory drift ratios (IDRs) were acquired from the floor response in time history analysis of a tall building subjected to selected ground motions. The FAA factors determined in this way are larger than those given in most current code provisions, but the obtained IDRs are close to the values given in some code provisions. Imposing a series of in‐plane pre‐deformations to two glass curtain wall (CW) specimens mounted on a shaking table, the IDRs were reproduced and the FAA factors were satisfied through applications of computed floor spectra compatible motion time histories, whose peak accelerations corresponded to the FAA factors. The CW specimens performed well during the whole experimental program with almost no change in the fundamental frequencies. No visible damage was observed in the glass panels. The maximum stresses detected in each component of the CW system were smaller than the design strengths. The obtained component acceleration amplification factor approached 3.35, which is larger than the value given in the current code provisions. In conclusion, the performance of the studied CW system is seismically safe. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Seismic response of 20‐story base‐isolated and fixed‐base reinforced concrete structural wall buildings at a near‐fault site 下载免费PDF全文
下载免费PDF全文 This paper investigates numerically the seismic response of six seismically base‐isolated (BI) 20‐story reinforced concrete buildings and compares their response to that of a fixed‐base (FB) building with a similar structural system above ground. Located in Berkeley, California, 2 km from the Hayward fault, the buildings are designed with a core wall that provides most of the lateral force resistance above ground. For the BI buildings, the following are investigated: two isolation systems (both implemented below a three‐story basement), isolation periods equal to 4, 5, and 6 s, and two levels of flexural strength of the wall. The first isolation system combines tension‐resistant friction pendulum bearings and nonlinear fluid viscous dampers (NFVDs); the second combines low‐friction tension‐resistant crosslinear bearings, lead‐rubber bearings, and NFVDs. The designs of all buildings satisfy ASCE 7‐10 requirements, except that one component of horizontal excitation, is used in the 2D nonlinear response history analysis. Analysis is performed for a set of ground motions scaled to the design earthquake and to the maximum considered earthquake (MCE). At both the design earthquake and the MCE, the FB building develops large inelastic deformations and shear forces in the wall and large floor accelerations. At the MCE, four of the BI buildings experience nominally elastic response of the wall, with floor accelerations and shear forces being 0.25 to 0.55 times those experienced by the FB building. The response of the FB and four of the BI buildings to four unscaled historical pulse‐like near‐fault ground motions is also studied. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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This paper investigates the cogency of various impact models in capturing the seismic pounding response of adjacent structures. The analytical models considered include the contact force‐based linear spring, Kelvin and Hertz models, and the restitution‐based stereomechanical approach. In addition, a contact model based on the Hertz law and using a non‐linear hysteresis damper (Hertzdamp model) is also introduced for pounding simulation. Simple analytical approaches are presented to determine the impact stiffness parameters of the various contact models. Parameter studies are performed using two degree‐of‐freedom linear oscillators to determine the effects of impact modelling strategy, system period ratio, peak ground acceleration (PGA) and energy loss during impact on the system responses. A suite of 27 ground motion records from 13 different earthquakes is used in the analysis. The results indicate that the system displacements from the stereomechanical, Kelvin and Hertzdamp models are similar for a given coefficient of restitution, despite using different impact methodologies. Pounding increases the responses of the stiffer system, especially for highly out‐of‐phase systems. Energy loss during impact is more significant at higher levels of PGA. Based on the findings, the Hertz model provides adequate results at low PGA levels, and the Hertzdamp model is recommended at moderate and high PGA levels. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献