Experimental evaluation of dynamic characteristics of seesaw energy dissipation system for vibration control of structures

Seesaw energy dissipation system (SEDS), a vibration control system used to provide enhanced seismic protection, has been proposed and investigated numerically. Because of its complicated arrangement, verification experiments are necessary to demonstrate the SEDS damping capacity. This paper presents the results of experimental investigation of the SEDS using fluid viscous dampers. Free vibration tests are conducted to demonstrate the SEDS damping capacity. Results of the free vibration test show that the SEDS has sufficient damping capacity for reduction of the seismic response of the frames. Parametric experimental investigations of the SEDS were conducted, the results of which demonstrate the effects of the system parameter on the damping capacity. Copyright © 2014 John Wiley & Sons, Ltd.     

有建筑物存在的饱和砂土地基液化振动台模拟实验研究

对建筑物地基的液化问题至今研究得尚不够充分。我们在已有的国内外研究成果的基础上,在已 有的振动台等试验条件下,做了一批试验,以进一步步证和完善已有的工作。     

软土地基核电厂房动力响应振动台试验

为了分析软土地基－筏基础核电厂房结构地震反应规律和特征,利用地震模拟振动台开展了软土地基－筏基础－核电厂房动力相互作用问题的试验研究。分别进行了表面水平土体模型和表面凹陷土体模型的运动相互作用试验、地基土－筏基础－核电厂房振动台相互作用试验、核电厂房直接固定在振动台面上的刚性基底振动台试验。试验采用圆形叠层剪切模型箱,地基土模型为某工程场地的均匀粉质粘土,其剪切波速为213 m/s;核电厂房简化为3层框架剪力墙结构模型。试验输入波形为美国核电规范常用的RG1.60反应谱合成得到的人工地震动时程。振动台试验结果对比分析表明:土－结构体系中系统的振动周期和阻尼明显大于刚性基底下结构的振动周期和阻尼;相同地震作用下在土－结构动力相互作用体系中结构加速度明显小于刚性基底下的结构加速度反应;而位移明显大于刚性基底下结构的位移。本文的研究成果可为软土地基建立核岛厂房的适应研究提供参考。     

村镇隔震砌体结构振动台试验方案设计研究

为使铅芯橡胶支座隔震技术应用于村镇砌体结构,将隔震层设置于地坪以上,本文给出了隔震构造的具体做法。选取典型村镇2层未设构造柱的砖砌体结构房屋为试验原型,按1:2缩尺,设计有隔震层和无隔震层的振动台对比试验。首先采用反应谱分析方法,对隔震和非隔震结构分别选取三条地震波,然后通过数值分析,研究隔震和非隔震结构在输入不同地震波时的地震反应规律,根据数值模拟的分析结果设计结构振动台试验中的传感器布置和加载方案。本文设计的砌体隔震振动台试验方案已试验成功,可为振动台试验设计和研究提供参考。     

Collapse behavior of a brick masonry house using a shaking table and numerical simulation based on the extended distinct element method

Damage caused by devastating earthquakes has occurred in many developing countries. In order to mitigate such damage by promoting the study of adequate seismic design strategies, the authors conducted a dynamic collapse test on 3 m × 3 m × 3 m brick masonry house constructed with Pakistani bricks, using a one-direction horizontal large-scale shaking table. In order to analyze and simulate seismic performance of the masonry structures, the authors applied a new numerical simulating method based on the Extended Distinct Element Method (EDEM) and conducted collapse simulations of the brick masonry house behavior during the shaking table tests. In the numerical simulation model, bricks were assumed to be rigid bodies, and mortar was modeled using a mortar spring that consists of a normal spring and a shear spring. The parameters of each mortar spring were defined based on the results of material tests. Simulated results showed various collapsing processes, and the simulated aspects were found to be similar to the results of the shaking table tests.     

Effect of near‐fault ground motion and damper characteristics on the seismic performance of chevron braced steel frames

This study is aimed at comparing the seismic performance of steel chevron braced frames (CBFs) with and without fluid viscous dampers (FVDs) as a function of the characteristics of the near‐fault (NF) ground motion and FVD parameters. For this purpose, comparative nonlinear time history (NLTH) analyses of single and multiple storey CBFs with and without FVDs are conducted using NF ground motions with various velocity pulse periods scaled to have small, moderate and large intensities. Additionally, NLTH analyses of single‐ and four‐storey CBFs with FVDs are conducted to study the effect of the damping ratio and velocity exponent of the FVD on the seismic performance of the frames. The analyses results revealed that the seismic performance of the CBFs without FVDs is very poor and sensitive to the velocity pulse period and the intensity of the NF ground motion due to brace‐buckling effects. Installing FVDs into the CBFs significantly improved their seismic performance by maintaining their elastic behaviour. Furthermore, FVDs with smaller velocity exponents and larger damping ratio are observed to be more effective in improving the seismic performance of the CBFs subjected to NF earthquakes. However, FVDs with damping ratios larger than 50% do not produce significant additional improvement in the seismic performance of the CBFs. Copyright © 2006 John Wiley & Sons, Ltd.     

PHC管桩单桩振动台试验与数值模拟对比分析

利用振动台对PHC管桩进行单桩承台模型试验;同时将土体PHC管桩-上部结构视为共同工作整体,建立三维有限元模型,再以ABAQUS软件为计算平台,对单桩试验工况下的地震反应进行数值模拟计算,并将试验结果与数值模拟计算结果进行对比分析。结果表明：数值模拟和振动台模型试验基本吻合,两者得到的地震反应影响体现出相似的规律性,印证了模型试验的可靠性和数值模型的合理性。     

特高压气体绝缘开关设备瓷套管抗震性能研究

为评估某型号1 100kV特高压(UHV)气体绝缘开关设备(GIS)瓷套管的抗震性能,将其连同支撑筒体与支架一起安装在振动台上,开展特高压气体绝缘开关设备瓷套管振动台试验。试验采用符合特高压标准反应谱的人工波激励该瓷套管,得到瓷套管关键部位的加速度、位移和应变响应。运用数值仿真软件ABAQUS对该振动台试验进行数值仿真研究,分析试验模型的自振频率、套管根部应力和套管顶端相对位移,得到与试验结果吻合较好的结果,证明该数值仿真模型的有效性。通过数值仿真的手段研究套管固有频率和本体(支撑筒体和支架)刚度的变化对套管抗震性能的影响,结果表明:该套管固有频率在一定范围内变化时,其地震响应相对较小;随着本体刚度的增大,套管根部最大应力与套管顶端最大相对位移均呈下降的趋势,因此适当增大本体的刚度可以降低套管的地震响应。     

Analysis of shaking table-structure interaction effects during seismic simulation tests

An analytical model is developed to evaluate performance characteristics of unidirectional seismic simulators (shaking tables). The validity of the model is verified with experimental measurements of the frequency response of the shaking table at the Catholic University of Peru. Interaction effects between shaking table and structure are first studied by analysing the response of a two DOF (degree of freedom) oscillator with mechanical properties representative of the actuator-table-structure system. A single DOF viscoelastic oscillator representing the structural test specimen is then included in the analytical model of the seismic simulator, and the behaviour of the combined system is evaluated, in the frequency domain, in terms of response stability and accuracy of reproduction of the command signal. Numerical simulations of system response under different load conditions are subsequently performed in order to study the influence of shaking table and test structure characteristics on the interaction phenomenon. The results obtained explain some of the performance degradation observed in seismic simulation tests involving very heavy structures and provide guidelines for the design of more reliable shaking table systems.     

电磁驱动AMD系统控制结构地震响应的振动台试验

本文在此前一系列有关新型电磁驱动AMD控制系统力学建模、性能试验和控制策略研究的基础上,进行了结构地震响应控制的小型振动台试验研究。首先,针对配置了电磁驱动AMD控制系统的Quanser标准两层剪切型框架结构模型,建立了无控计算模型,通过正弦扫频试验验证了模型参数,从而为结构振动主动控制试验研究提供了准确的被控对象模型;其次,设计了电磁驱动AMD控制系统基于极点配置控制算法的试验控制策略和状态观测器,通过数值分析验证了状态观测器估计结果的准确性;最后,在完成以上各项准备工作的基础上,分别对结构输入了典型Benchm ark标准地震动,进行振动台试验,试验结果表明电磁驱动AMD控制系统对结构的地震响应具有显著的控制效果,验证了该新型系统应用于结构振动控制的有效性和可行性。     

Investigation of the seismic response of high‐rise buildings supported on tension‐resistant elastomeric isolation bearings

In many applications of seismic isolation, such as in high‐rise construction, lightweight construction, and structures with large height‐to‐width aspect ratios, significant tension forces can develop in bearings, raising concerns about the possible rupture of elastomeric bearings and the uplift of sliding bearings. In this paper, a novel tension‐resistant lead plug rubber bearing (TLRB) with improved tension‐resisting capabilities is developed and experimentally and numerically assessed. This TLRB consists of a common lead plug rubber bearing (LRB) and several helical springs. After describing the theory underlying the behavior of the TLRB, the mechanical properties of reduced‐scale prototype bearings are investigated through extensive horizontal and vertical loading tests. The test results indicate that TLRBs can improve the shear stiffness and tension resistance capacity even under significant tensile loads. A series of shaking table tests on scaled models of high‐rise buildings with different aspect ratios were conducted to investigate the dynamic performance of the TLRB and the seismic responses of base‐isolated high‐rise buildings. Three different cases were considered in the shaking table tests: a fixed base condition and the use of TLRB and LRB isolation systems. The results of the shaking table test show that (a) base‐isolated systems are effective in reducing the structural responses of high‐rise buildings; (b) an isolated structure's aspect ratio is an important factor influencing its dynamic response; (c) TLRBs can endure large tensile stresses and avoid rupture on rubber bearings under strong earthquakes; and (d) the experimental and numerical results of the responses of the models show good agreement. Copyright © 2016 John Wiley & Sons, Ltd.     

Nonlinear response spectra of cable net facades

Cable net facades are widely used as a new kind of glazing system and have many advantages, such as pleasing esthetics and easy constructability. With the characteristics of low stiffness, light weight, and small damping, cable net facades are obviously geometrically nonlinear, and the response spectrum method may have some limitations in the seismic design of cable net façades. Therefore, the nonlinear vibration differential equation and natural frequency of the cable net subject to earthquakes was deduced, and then the geometrically nonlinear single-degree of freedom model was founded. Second, with the geometrically nonlinear single-degree of freedom model, the nonlinear seismic response of the cable net was calculated with the time history method subject to four groups of site conditions, and the nonlinear response spectra were founded. Third, the linear and nonlinear acceleration and displacement spectra were compared thoroughly. Lastly, shaking table tests were conducted to verify the accuracy of the nonlinear response spectra.     

Shaking table experimental study of recycled concrete frame-shear wall structures

In this study, four 1/5 scaled shaking table tests were conducted to investigate the seismic performance of recycled concrete frame-shear wall structures with different recycled aggregates replacement rates and concealed bracing detail. The four tested structures included one normal concrete model, one recycled coarse aggregate concrete model, and two recycled coarse and fi ne aggregate concrete models with or without concealed bracings inside the shear walls. The dynamic characteristics, dynamic response and failure mode of each model were compared and analyzed. Finite element models were also developed and nonlinear time-history response analysis was conducted. The test and analysis results show that the seismic performance of the recycled coarse aggregate concrete frame-shear wall structure is slightly worse than the normal concrete structure. The seismic resistance capacity of the recycled concrete frame-shear wall structure can be greatly improved by setting up concealed bracings inside the walls. With appropriate design, the recycled coarse aggregate concrete frame-shear wall structure and recycled concrete structure with concealed bracings inside the walls can be applied in buildings.     

考虑不同固定条件的核电设备多维地震响应振动台试验研究

在核电站中:核电设备通过不同的固定条件与结构相连,地震作用时设备与结构动力相互作用复杂,为分析核电设备多维地震响应并鉴定其抗震性能,进行了考虑不同固定条件的核电设备多维地震响应振动台试验研究。振动台试验进行了5次运行基准地震和1次安全停堆地震的动力时程激振,以及试验首末2次动力特性测试。试验结果表明:不同固定条件会影响核电设备多维地震响应的加速度峰值、反应谱特性和动力放大系数,与设备直接固定于振动台相比,将核电设备悬挂固定于剪力墙再与振动台连接的固定条件,改变了设备反应谱特性,且放大了响应的加速度峰值,具有显著的动力放大效应,使核电设备多维地震响应更为强烈。因此,对此类固定条件的核电设备,在产品设计及安装固定时要充分考虑动力放大效应,以提高设备的抗震韧性。抗震试验前后,核电设备功能运行正常,结构完整性好,抗震性能满足要求。     

多点激励下拱桥模型振动台试验及数值模拟研究

对多点激励下大跨度桥梁的抗震性能研究,目前主要集中在理论和数值模拟方面,缺乏振动台试验数据的验证。本文通过对一座拱桥模型的多点激励振动台试验和相应的数值模拟分析,在一定程度上揭示了拱桥在一致激励、考虑行波效应和衰减效应的多点激励下的反应特点。同时,本文的数值模拟结果与试验结果也得到了较好的吻合。     

SEISMIC TESTING OF A BUILDING STRUCTURE WITH A SEMI-ACTIVE FLUID DAMPER CONTROL SYSTEM

This paper describes shaking table tests of a multi-storey scale-model building structure subjected to seismic excitation and controlled by a semi-active fluid damper control system. The semi-active dampers were installed in the lateral bracing of the structure and the mechanical properties of the dampers were modified according to control algorithms which utilized the measured response of the structure. A simplified time-delay compensation method was developed to account for delays within the control system. The results of the shaking table tests are presented and interpreted and analytical predictions are shown to compare reasonably well with the experimental results. © 1997 John Wiley & Sons, Ltd.     

Study on effects of damping in laminated rubber bearings on seismic responses for a ⅛ scale isolated test structure

The effects of damping in various laminated rubber bearings (LRB) on the seismic response of a ?‐scale isolated test structure are investigated by shaking table tests and seismic response analyses. A series of shaking table tests of the structure were performed for a fixed base design and for a base isolation design. Two different types of LRB were used: natural rubber bearings (NRB) and lead rubber bearings (LLRB). Three different designs for the LLRB were tested; each design had a different diameter of lead plug, and thus, different damping values. Artificial time histories of peak ground acceleration 0.4g were used in both the tests and the analyses. In both shaking table tests and analyses, as expected, the acceleration responses of the seismically isolated test structure were considerably reduced. However, the shear displacement at the isolators was increased. To reduce the shear displacement in the isolators, the diameter of the lead plug in the LLRB had to be enlarged to increase isolator damping by more than 24%. This caused the isolator stiffness to increase, and resulted in amplifying the floor acceleration response spectra of the isolated test structure in the higher frequency ranges with a monotonic reduction of isolator shear displacement. Copyright © 2002 John Wiley & Sons, Ltd.     

结构-地基动力相互作用体系振动台模型试验研究

本文设计实现了结构－地基动力相互作用体系的振动台试验,通过试验研究了动力相互作用体系的地震动反应的主要规律,由于动力相互作用的影响,软土地基中相互作用体系的频率远小于刚性地基上不考虑结构－地基相互作用的结构频率,而阻尼比例则远大于结构材料阻尼比,软上地基对地震动走滤波和隔震作用,由于上部结构的振动反馈,基底地震动与自由场地震动不相同,上部结构柱顶加速度反应主要由基础转动引起的摆动分量组成,平均分量次之,而弹性变形分量很小,桩身应变幅值呈桩顶大,桩尖小的倒三角形分布,桩上接触压力幅值呈桩顶小,桩尖大的三角形分布,试验表明,结构－地基动力相互作用对体系地震反应的影响是很是显著的,本试验为验证理论与计算分析的研究成果,改进或提出合理的计算模型和分析方法,提出了丰富的试验数据,为进一步研究奠定的基础。     

考虑土与结构相互作用效应的结构减震控制大型振动台模型试验研究

本文设计并完成了考虑土与结构相互作用的结构减震控制大型振动台模型试验。通过对四种结构形式的对比试验，探讨了土与结构相互作用（ＳＳＩ）效应对结构地震反应的影响以及调谐质量阻尼器（ＴＭＤ）在刚性和柔性地基条件下对主体结构的减震效应。通过比较同一地震动作用下主体结构在刚性和柔性两种地基条件下的地震反应，可知：ＳＳＩ效应具有降低和提高结构减震控制效果的双重作用，其综合效果与输入地震动的频谱特性、加速度峰值大小有关。由于ＳＳＩ效应在结构地震反应中发挥着双重的作用，因而使得基于刚性地基假定下设计的ＴＭＤ减震控制系统在柔性地基条件下的控制效果不太理想，甚至会出现负面效应。本文还探讨了在柔性地基条件下影响结构减震控制效果的一些因素。     

A substructure shaking table test for reproduction of earthquake responses of high‐rise buildings

When subjected to long‐period ground motions, high‐rise buildings' upper floors undergo large responses. Furniture and nonstructural components are susceptible to significant damage in such events. This paper proposes a full‐scale substructure shaking table test to reproduce large floor responses of high‐rise buildings. The response at the top floor of a virtual 30‐story building model subjected to a synthesized long‐period ground motion is taken as a target wave for reproduction. Since a shaking table has difficulties in directly reproducing such large responses due to various capacity limitations, a rubber‐and‐mass system is proposed to amplify the table motion. To achieve an accurate reproduction of the floor responses, a control algorithm called the open‐loop inverse dynamics compensation via simulation (IDCS) algorithm is used to generate a special input wave for the shaking table. To implement the IDCS algorithm, the model matching method and the H_∞ method are adopted to construct the controller. A numerical example is presented to illustrate the open‐loop IDCS algorithm and compare the performance of different methods of controller design. A series of full‐scale substructure shaking table tests are conducted in E‐Defense to verify the effectiveness of the proposed method and examine the seismic behavior of furniture. The test results demonstrate that the rubber‐and‐mass system is capable of amplifying the table motion by a factor of about 3.5 for the maximum velocity and displacement, and the substructure shaking table test can reproduce the large floor responses for a few minutes. Copyright © 2009 John Wiley & Sons, Ltd.