Aseismic smart building isolation systems under multi-level earthquake excitations: Part I,conceptual design and nonlinear analysis

As a novel structural control strategy, tuned mass damper (TMD) inspired passive and semi-active smart building isolation systems are suggested to reduce structural response and thus mitigate structural damage due to earthquake excitations. The isolated structure’s upper stories can be utilized as a large scaled TMD, and the isolation layer, as a core design point, between the separated upper and lower stories entails the insertion of rubber bearings and (i) viscous dampers (passive) or (ii) resettable devices (semi-active). The seismic performance of the suggested isolation systems are investigated for 12-story reinforced concrete moment resisting frames modeled as “10+ 2” stories and “8+ 4” stories. Passive viscous damper or semi-active resettable devices are parametrically evaluated through the optimal design principle of a large mass ratio TMD. Statistical performance metrics are presented for 30 earthquake records from the three suites of the SAC project. Based on nonlinear structural models, including P-delta effects and modified Takeda hysteresis, the inelastic time history analyses are conducted to compute the seismic performances across a wide range of seismic hazard intensities. Results show that semi-active smart building isolation systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions in comparison to uncontrolled case and passive solution.     

碟形弹簧竖向减震装置的性能试验研究

基础隔震技术是目前应用最广泛的结构控制方法,但是,目前这种技术只是最大限度地减少或隔离水平地震作用,而对竖向地震作用几乎没有影响。为改善隔震技术在隔离竖向地震中的限制,研制了一种由碟形弹簧和粘弹性阻尼器组合而成的碟形弹簧竖向减震装置,并对其进行了在静载和动载作用下的力学性能试验研究, 给出了该装置在竖向静力和动力作用下的等效刚度和阻尼比,建立了恢复力模型,试验研究表明,碟形弹簧竖向减震装置能有效的解决竖向大承载力和竖向阻尼的难题,力学性能优良且稳定,加工制作容易,是一种比较理想的竖向减震装置。     

Finite element formulations and theoretical study for variable curvature friction pendulum system

The friction pendulum system (FPS), a type of base isolation technology, has been recognized as a very efficient tool for controlling the seismic response of a structure during an earthquake. However, previous studies have focused mainly on the seismic behavior of base-isolated structures far from active earthquake faults. In recent years, there have been significant studies on the efficiency of the base isolator when subjected to near-fault ground motions. It is suggested from these studies that the long-duration pulse of near-fault ground motions results in significant response of a base-isolated structure. In view of this, an advanced base isolator called the variable curvature friction pendulum system (VCFPS) is proposed in this study. The radius of the curvature of VCFPS is lengthened with an increase of the isolator displacement. Therefore, the fundamental period of the base-isolated structure can be shifted further away from the predominant period of near-fault ground motions. Finite element formulations for VCFPS have also been proposed in this study. The numerical results show that the base shear force and story drift of the superstructure during near-fault ground motion can be controlled within a desirable range with the installation of VCFPS. Therefore, the VCFPS can be adopted for upgrading the seismic resistance of the structures adjacent to an active fault.     

组合隔震技术在高烈度区复杂高层结构中的应用研究

为探讨近断层的复杂高层建筑结构的隔震设计要点,结合某高层医院建筑结构设计实例,研究9度设防强地震输入、体型特别不规则和高预期抗震性能目标条件下采用隔震技术的适应性及对应措施,提出发挥不同隔震器件和减震装置性能特点的组合隔震技术方法。结果表明,组合隔震可减小隔震橡胶支座面压和水平变形,减少塔楼偏置引起的结构扭转效应、竖向高位收进引起的高振型效应,结构构件损伤程度和范围大幅降低,屈服耗能机制更为合理,有效提升了建筑结构的抗震能力。分析比较近场速度脉冲型地震波与考虑1.5近场增大系数的常规地震波作用下复杂高层隔震结构的地震响应差别,结果表明,在速度脉冲型地震波作用下的隔震层位移、上部结构层间位移角及层剪力均大于考虑1.5近场增大系数的常规地震波,采用1.5近场增大系数不能包络近场地震效应,隔震设计时应慎重考虑。     

Application research of combined isolation technology in complex high-rise building in high seismic intensity region

为探讨近断层的复杂高层建筑结构的隔震设计要点，结合某高层医院建筑结构设计实例，研究9度设防强地震输入、体型特别不规则和高预期抗震性能目标条件下采用隔震技术的适应性及对应措施，提出发挥不同隔震器件和减震装置性能特点的组合隔震技术方法。结果表明，组合隔震可减小隔震橡胶支座面压和水平变形，减少塔楼偏置引起的结构扭转效应、竖向高位收进引起的高振型效应，结构构件损伤程度和范围大幅降低，屈服耗能机制更为合理，有效提升了建筑结构的抗震能力。分析比较近场速度脉冲型地震波与考虑1.5近场增大系数的常规地震波作用下复杂高层隔震结构的地震响应差别，结果表明，在速度脉冲型地震波作用下的隔震层位移、上部结构层间位移角及层剪力均大于考虑1.5近场增大系数的常规地震波，采用1.5近场增大系数不能包络近场地震效应，隔震设计时应慎重考虑。     

近断层水平-竖向地震作用下基础隔震结构的动力响应

基础隔震技术在目前的结构分析和设计过程中,对于冲击性较强的近断层地震作用考虑甚少,特别是竖向分量考虑更少.通过选取1999年台湾集集地震中,含有完整水平与竖向地震分量的近断层记录、远场地震记录以及断层附近非脉冲型地震记录作为地震输入,分析基础隔震结构在近断层水平-竖向地震分量共同作用下的动力响应,以及隔震支座的受力状态...     

Parametric study on the Multangular-Pyramid Concave Friction System (MPCFS) for seismic isolation

A series of comprehensive parametric studies are conducted on a steel-frame structure Finite-Element (FE) model with the Multangular-Pyramid Concave Friction System (MPCFS) installed as isolators. This new introduced MPCFS system has some distinctive features when compared with conventional isolation techniques, such as increased uplift stability, improved self-centering capacity, non-resonance when subjected to near-fault earthquakes, and so on. The FE model of the MPCFS is first established and evaluated by comparison between numerical and theoretical results. The MPCFS FE model is then incorporated in a steel-frame structural model, which is subjected to three chosen earthquakes, to verify its seismic isolation. Further, parametric study with varying controlling parameters, such as isolation foundation, inclination angle, friction coefficient, and earthquake input, is carried out to extract more detailed dynamic response of the MPCFS structure. Finally, limitations of this study are discussed, and conclusions are made. The simulations testify the significant seismic isolation of the MPCFS. This indicates the MPCFS, viewed as the beneficial complementary of the existing well-established and matured isolation techniques, may be a promising tool for seismic isolation of near-fault earthquake prone zones. This verified MPCFS FE model can be incorporated in future FE analysis. The results in this research can also guide future optimal parameter design of the MPCFS.     

SMA复合支座与磁流变阻尼器的双重隔震体系减震效果分析

为了进一步改善SMA复合支座在强震下的隔震效果,特别是当复合支座的水平剪切变形较大时,将SMA复合支座与磁流变阻尼器相结合,建立一种基于SMA复合支座与磁流变阻尼器的双重隔震体系及其力学模型,并与单纯的SMA复合支座隔震进行对比。仿真分析表明,该体系不仅能够大幅度地减小隔震层的水平侧移,有效地保护隔震装置,而且能使上部结构的层间位移与加速度反应得到有效的控制,从而提高隔震建筑的减震效果和可靠性。     

Theoretical and experimental study on seismic response control on top of Three-Gorges ship lift towers using magnetorheological intelligent isolation system and its key technique

A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers. This paper proposes a roof magnetorheological (MR) intelligent isolation system to prevent the seismic whipping effect on machinery structures. Theoretically, the dynamic models of MR damper and the mechanical model of ship lift was established, the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced. Experimentally, the experimental model of the ship lift was given, the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared. In practical aspect, the large-scale MR damper (500 kN) and a sliding support with limited stiffness were designed and fabricated. It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.     

大坝升船机地震鞭梢效应智能控制的振动台试验

大坝升船机顶部厂房与底部塔柱结构之间的侧移刚度突变造成了顶部厂房强烈的地震鞭梢效应。针对此问题,本文进行了屋盖MR智能隔震系统对大坝升船机地震鞭梢效应智能控制的振动台试验研究。屋盖MR智能隔震系统由隔震垫、磁流变(MR)阻尼器及控制系统组成,安装在厂房的柱子顶部。首先采用修正的Bingham模型得到数据来训练神经网络以反映MR阻尼器的逆向动力特性,然后与模糊算法结合通过dSPACE实时控制系统得到阻尼器的最优控制信号。试验结果表明:模糊-神经控制方法能有效控制屋盖MR智能隔震系统,使得大坝升船机顶部厂房的鞭梢效应明显减小,排架柱顶位移减小了50%,隔震层相对位移减小了57%。     

远场长周期地震动下桩-土-层间隔震结构振动台试验研究

软土地基条件下土-结构相互作用(SSI)效应会对隔震结构的减震效果及动力特性产生影响。远场长周期地震动使隔震建筑这类长周期结构地震响应强烈,考虑SSI效应后地震响应可能更大。开展软土地基上层间隔震结构模型振动台试验研究,对比分析远场长周期和普通地震动下隔震层和隔震结构的楼层加速度和位移响应,研究远场长周期地震动下桩-土-层间隔震结构动力响应规律及减震效果。结果表明：软土地基具有明显的滤波效应,抑制高频分量,放大中低频分量;普通地震动下层间隔震结构的减震效果较显著,随着输入加速度峰值增大,减震效果降低,而远场长周期地震动下的层间隔震结构的减震效果比普通地震动下的差;基础及隔震层的转动效应明显,隔震层对基础转动有一定放大效应,远场长周期地震动下的隔震结构的放大效应较普通地震动下的明显,并对隔震层位移反应的影响较大。     

Analytical and Numerical Study of a Smart Sliding Base Isolation System for Seismic Protection of Buildings

The seismic response of a single–story steel building frame with a smart base isolation system is evaluated. The isolation system consists of sliding bearings combined with an adaptive fluid damper. The damping capacity of the fluid damper can be modulated in real time based on feedback from the earthquake ground motion and superstructure response. The adaptive capabilities of the fluid damper enable the isolation system displacement to be controlled while simultaneously limiting the interstory drift response of the superstructure. This paper concentrates on the development of analytical models of the smart isolation system and control algorithms for operation of the system. In general, the results from numerical simulations demonstrate that, for disparate earthquake ground motions, the smart isolation system is capable of simultaneously limiting both the response of the isolation system and the superstructure.     

脉冲地震作用下千米级斜拉桥减震设计方法

为研究近断层脉冲地震动作用下千米级斜拉桥的减震设计方法,以某漂浮型千米级斜拉桥为背景,建立了有限元模型,选择了典型的近断层脉冲型地震动,同时设计了3种减震体系,在塔梁之间分别采用弹性连接装置、流体粘滞阻尼器以及两者的组合装置。随后对模型进行了非线性动力分析,分析了脉冲效应、减震体系的设计参数和减震效果,结果表明:脉冲长周期放大结构反应,剪切波速不影响结构反应,组合装置的减震效果最好。最后,建议了基于目标减震率的减震体系设计流程。     

拟负刚度磁流变智能隔震系统振动台试验研究

为研究拟负刚度控制算法及磁流变智能隔震系统的有效性和适应性,将自主研发的最大出力为10kN的磁流变液阻尼器(MRFD)安装在隔震层中心,并选取4条有代表性的远近场地震波,峰值加速度由0.1g~0.9g逐步增大,分别对普通隔震结构、输入电流为0A和1A的被动控制结构以及采用基于位移的拟负刚度(DPNS)控制算法的智能控制结构进行振动台试验。通过对结构响应和阻尼器响应的对比分析,研究拟负刚度控制算法的减震效果和磁流变智能控制系统的耗能特性。结果表明：恒定电流为0A的被动控制可同时降低上部结构反应和隔震层位移,但是减震效果有限;恒定电流为1A的被动控制对隔震层位移降低效果明显,但是在多遇地震及远场地震作用下放大了上部结构反应;DPNS控制可同时降低隔震层位移和多遇、设防地震甚至罕遇地震作用下上部结构的反应,且适应于不同的地震动特性;试验中控制系统存在的时滞效应使得DPNS控制力在多遇、设防地震作用下具有较小值,同时罕遇地震作用下具有较强的耗能能力。     

消能摇摆高位隔震结构体系的地震反应特性

双段消能摇摆结构体系是通过两段串联的摇摆结构,控制主体结构各楼层在地震作用下均匀变形,抑制薄弱层的产生,也降低了主体结构对于摇摆结构的刚度需求。在变形集中的摇摆结构底部布设位移型阻尼器,可进一步提高结构的抗震性能。但是该体系存在承载力较低、上段结构地震反应相对较大的不足。基于此,提出了消能摇摆高位隔震结构体系,即在双段消能摇摆结构体系的分段楼层位置增设劲性支撑,以抑制上段结构的摇摆运动,提高结构的刚度与承载力;同时,下段结构允许发生摇摆,发挥高位隔震层的作用。以消能摇摆高位隔震结构体系为研究对象,分析对比了其他三种结构体系：传统支撑框架结构体系、双段消能摇摆结构体系、不含位移型阻尼器的摇摆高位隔震结构体系。采用OpenSees软件建立了弹塑性有限元分析模型,对四种结构体系进行弹塑性抗震分析和增量动力时程分析。研究表明,消能摇摆高位隔震结构体系的刚度与承载力较高,地震反应较小,抗震性能与抗倒塌性能良好。在摇摆结构分段位置加设劲性支撑层,可以抑制上段结构在地震作用下的变形,并发挥下段摇摆结构的隔震作用。布设于分段位置与摇摆结构底部的阻尼器,可以充分消耗地震能量,提高结构体系的抗震性能。     

结构半主动变刚度控制的研究

尽管已有的研究证明传统的变刚度控制系统可以有效地抑制结构在地震激励下动力响应,但是现有的变刚度装置仅能在很小的范围内改变结构的周期,而且也不利于抑制结构的加速度反应。为了克服这一局限性,本文提出了一种新型的半主动变刚度(ISAVS)控制系统,兼具基础隔震和传统变刚度控制的优点。基于作者提出的离复位控制策略,本文针对ISAVS系统进行了地震作用下的数值模拟,验证了它的可行性和有效性。     

近断层/远场地震动作用下控制性岩体结构对地下洞室地震稳定性影响研究

 当前地下岩石工程地震响应研究中,缺乏对近断层地震动的影响机制的研究,也较少考虑地下岩石工程赋存环境中的地质结构。采用一种非线性节理本构模型模拟不利地质结构面,结合从NGA-West2数据库中选取的近断层脉冲型、近断层无脉冲型、及远场地震记录,分析近断层地震动对不利地质结构地震破坏现象的影响机制,并讨论、提出不利地质结构的地震动潜在破坏势,最后针对受层间错动带C2切割控制的白鹤滩水电站左岸尾水系统1#尾调室,揭示其在近断层脉冲型、无脉冲型、远场地震动作用下的动力响应与稳定性的差异。初步研究结果表明：(1) 仅有近断层脉冲型地震动才具有较大的速度、位移峰值和反应谱长周期值的特点,而近断层无脉冲型地震动特性与远场地震动近似;(2) 相对于近断层的大幅值,速度脉冲才是导致近断层地震动具有较大破坏能力的根本原因,速度脉冲使得岩体结构面两盘产生不可接受的剪切位移,成为洞室在近断层地震动作用下独特的失稳机制;(3) 对于地下工程中的不利地质结构而言,相比最常用的地震动强度参数PGA,PGV,PGD和PGV/PGA是为更理想的地震动潜在破坏势,且近断层/远场地震动可适用一种破坏势;(4) 提出的潜在破坏势参数在白鹤滩尾水系统1#尾调室的地震响应分析中得到了较好的验证,若受近断层脉冲型地震动的影响,洞室可能处于不稳定状态,可能需要针对性的抗震支护措施。结论可供地下洞室的抗震设计与分析参考。     

基础隔震结构中上部结构与隔震层的刚度比限值研究

以控制结构变形为目标,将上部结构刚度与隔震层刚度的比值定义为隔震刚度比,作为反映上部结构与隔震层协同变形特点的指标。假定上部结构的地震作用沿高度为矩形分布,在一般结构单质点简化方法基础上提出一种隔震结构动力分析的等效简化方法。进一步分析双自由度等效模型的刚度影响和动力特性,以隔震刚度比的形式解释了结构位移需求、位移分配函数以及隔震刚度比对结构抗震性能的影响。基于抗震性能,推导出结构位移需求与周期关系式、临界隔震刚度比表达式、最大和最小隔震刚度比限值表达式。选取不同结构高度、地震烈度、阻尼条件等计算了上部形式为框架、框-剪、剪力墙结构的三类隔震结构在罕遇地震作用下的隔震刚度比限值。结果表明,一般隔震结构的隔震刚度比限值不宜小于4,低多层隔震结构主要由最小隔震刚度比控制,高层隔震结构在特定条件下需要满足最大隔震刚度比限值。计算结果整理成表格可供设计参考。     

基于弹塑性限位装置的基础隔震建筑地震碰撞行为

在近场速度脉冲型地震作用下,基础隔震建筑可能产生过大的支座变形,为了防止结构和隔震沟边缘产生刚性碰撞并对上部结构造成损伤,建议在隔震层高度用弹塑性限位装置来防止结构产生过大位移并实现一定程度的消能减震。提出了一组动力学方程,将建筑结构模型和Bouc-Wen单元串联,可以考虑隔震间隙的非线性动力响应。考虑了速度脉冲周期对结构响应的放大作用,根据弹塑性动力碰撞分析方程,以3组不同高度的钢框架结构基准模型为算例,计算了限位装置的弹性刚度和屈服力等因素对不同结构的弹塑性响应。结果表明：恰当选取用于碰撞限位的弹塑性限位装置的碰撞刚度与屈服力,既能有效限制隔震层的水平位移,上部结构也不会产生过大的反向动力响应,能够充分保护结构;在较易激发类共振效应的速度脉冲型地震动作用下,上部结构最大响应同弹塑性限位装置的弹性刚度与屈服力呈正相关性。     

串联隔震结构震损倒塌动态模型分析

建立了叠层橡胶隔震垫与地下室悬臂RC柱组成的串联隔震结构的有限元分析模型,编写了利用MSC.MARC软件生死单元二次开发UACTIVE程序来模拟隔震垫的失效,并分析了远场多维地震激励下不同长细比悬臂柱柱顶加连梁对结构响应的影响,同时分析了设置阻尼器控制隔震层位移后的结构地震响应。分析表明:通过生死单元二次开发程序可以有效地模拟隔震垫破坏;实际工程中常规的长细比悬臂柱柱顶加连梁对串联隔震结构的响应影响微小;隔震层增设非线性阻尼器可以控制位移且不影响多遇地震下的隔震效果。