结构抗震试验方法的发展

地震荷载极大的破坏性,使得结构抗震性能的研究成为一个被广泛关注的热点问题.为了提高结构抗震研究的试验能力和试验水平,近年来在传统结构抗震试验方法的基础上,出现了一些新的试验方式和方法.本文总结介绍了目前结构抗震试验方法的一些发展趋势,包括：（1）地震模拟振动台的大型化和多台化,以进行大比例模型甚至足尺模型试验或考虑大跨度结构地震动的非均匀性;（2）进行子结构试验的实时化,以实现数值子结构模型和试验子结构模型的实时结合;（3）进行试验设备的网络化,以提高试验设备的利用率,实现资源共享等,供有关研究者参考.     

抗震建筑结构研究方法述评

在参阅大量参考资料的基础上,综述了抗震建筑结构的研究方法.     

中国古代木构建筑抗震机理及抗震加固效果的试验研究

为探究中国古代大木作(带有斗栱的木构建筑)结构抗震机理和抗震加固的有效方法，对缩尺比为1／3．52二等材宫殿当心间模型在同样条件下分别进行了模拟地震动的振动台试验研究，测试了模型结构加速度、速度和位移的动力时程响应；模型结构的自震频率和阻尼比。结果表明，古代大木作结构的抗震机理主要表现为两个方面：(i)因柱根滑移而隔震;(ii)斗栱以及普柏枋因弹塑性变形和摩擦滑移消耗掉大量地震能以致结构减轻了震害。     

磁流变阻尼器的半主动控制及实时混合模拟试验研究

磁流变阻尼器作为一种比较典型的半主动控制元件,具有构造简单、响应速度快、耐久性好、阻尼力大且连续可调等优点。即使地震中能源中断,磁流变阻尼器仍可以作为被动耗能装置继续工作发挥作用,可靠性高。设计合理有效的磁流变阻尼器半主动控制方法,对于整体结构的减震效果尤其重要。提出一种改进的磁流变阻尼器的半主动控制策略-改进的Bang-Bang控制策略,对装有磁流变阻尼器的减震控制3层框架结构进行了一系列的实时混合模拟试验,对多种半主动控制方法下的振动控制效果进行试验分析。试验结果表明:磁流变阻尼器对框架结构的减震效果显著,并验证了提出的磁流变阻尼器半主动控制策略的有效性。     

基于虚拟振动台的实时耦联动力仿真试验

实时耦联动力试验(RTDHT)是一种将物理模型试验与数值求解计算实时耦联在一起的新型结构动力试验方法.本文采用SIMULINK对液压伺服振动台系统进行了仿真,建立虚拟振动台模型对真实振动台进行离线调试.并提出基于虚拟振动台进行实时耦联动力仿真试验,从而对真实实时耦联动力试验进行指导的思想.仿真结果表明,虚拟振动台可以很好地仿真真实振动台的动力特性,离线调试结果应用于真实振动台能够得到优良的控制性能;基于虚拟振动台的实时耦联动力仿真试验能够反映真实实时耦联动力试验中存在的时滞以及由此而可能导致的系统失稳问题.采用预测补偿算法对时滞进行了补偿,结果表明补偿算法消除了时滞的影响,试验系统稳定且试验结果与数值计算结果吻合得较好.基于虚拟振动台对实时耦联动力试验进行研究,既能对真实试验提出指导又可避免试验系统失稳对设备的损害,是一种实用且必要的研究手段.     

同高宽比弹塑性隔振建筑结构的抗震性能试验研究

研究以某同高宽比弹塑性隔振建筑结构为工程实例,采用SAP2000软件构建了同高宽比弹塑性隔振建筑结构的有限元模型,并进行了模型材料和相应参数选取;在此基础上,利用循环侧推分析隔振建筑结构中各构件的内力及变形情况,建立隔震建筑结构损失模型,同时为了提高其抗震性评估精准度,采用动力弹塑性顶层位移情况反应隔震建筑结构的抗震性能。工程实例分析结果表明,普通建筑结构主要控制层间位移响应,无论是在8度频发地震作用下还是在8度特大地震作用下,隔震建筑结构的顶部加速度响应均远远小于普通建筑结构,且仍然处于完全弹性工作状态,结构构件并未发生破坏,保证了建筑内部人们的生命财产安全,同时便于震后快速修复,相比于普通建筑结构,同高宽比弹塑性隔振建筑结构的抗震性能更优。     

室内管道系统抗震研究综述

根据最新震害统计资料发现,非结构构件在地震中造成的经济损失远大于结构构件。非结构构件按照地震反应特征可分为位移敏感型构件和加速度敏感型构件。其中,位移敏感型构件的破坏多受层间位移角控制,主要采用拟静力试验进行研究;加速度敏感型构件的破坏多受楼面加速度的控制,主要采用振动台试验进行研究。室内管道系统是非结构构件的重要组成部分,室内管道系统中的立管和水平管分别属于位移敏感型和加速度敏感型构件。本文系统地论述了近年来国内外学者开展的关于室内管道系统的抗震研究工作,并对室内管道系统下一步的研究工作提出了建议。     

三峡升船机塔柱结构抗震试验研究

通过在大型三向六自由度振动台进行三峡升船机塔柱结构的抗震试验,并辅助以动力计算分析研究,确定了升船机塔柱结构的固有频率,振型及阻尼比等动力特性,得到了升船机塔柱结构沿主轴方向的设计地震作用下的动力反应,评价三峡升船机塔柱结构的抗震安全性。对影响机房设备安全运行的各塔柱顶部最大地震相对位移进行论证。     

重力坝大孔口坝段抗震试验研究

以景洪水电站重力坝大孔口坝段为研究对象,通过输入没特性地震波的振动台模型试验和三维有限元分析,定量、定性地研究了大孔口坝段地震反应的特性。结果表明,对于大孔口坝段使用现行抗震规范反应谱曲线乍得的结果偏小;用振型迭加计算大孔坝段地震响应,参与迭加的振型不应少于五阶;应充分考虑不同地震特性的影响。     

新型抗震支吊架振动台试验研究

在地震作用下,抗震支吊架理应保障建筑机电工程设施和管道系统均具备良好的服役性能。因此,对抗震支吊架的抗震性能进行检测至关重要。本文以某典型地下室抗震支吊架为对象开展了顺管向地震模拟振动台试验,通过多工况试验对比分析了不同支吊架的位移和加速度的地震响应。试验结果表明:抗震支吊架显著降低了管道位移,减振率最高可达到96%,但对于加速度响应的抑制作用较小。易损性分析表明:采用成品支吊架时,管道系统在遭受相当于设防烈度的地震作用时会发生严重损伤,而采用抗震支吊架的管道系统能够保全其功能。     

高强度地震下带钢避难建筑抗震设计

为了提高带钢避难建筑的抗震性能,对高强度地震下带钢避难建筑实施抗震设计。设置高强度地震下带钢避难所的抗震设防要求,给出不同地震情况下地震避难所设防加速度值以及地震避难所地震影响系数最高值,通过SAP2000分析软件对带钢地震避难建筑结构实施动力弹塑性时程研究,选择合理的塑性铰参数值,通过在建筑周围设置钢支撑的策略对带钢避难建筑实施设计,分析高强度地震下的带钢避难建筑的抗震性能。实验结果说明,采用所提设计方法下的带钢避难建筑在大震情况下的反应优,延性较强,在不同地震波作用下的水平方向位移角满足抗震设防规范。     

Compensation of time‐delay for control of civil engineering structures

Time‐delay is an important issue in structural control. Applications of unsynchronized control forces due to time‐delay may result in a degradation of the control performance and it may even render the controlled structures to be unstable. In this paper, a state‐of‐the‐art review for available methods of time‐delay compensation is presented. Then, five methods for the compensation of fixed time‐delay are presented and investigated for active control of civil engineering structures. These include the recursive response method, state‐augmented compensation method, controllability based stabilization method, the Smith predictor method and the Pade approximation method, all are applicable to any control algorithm to be used for controlled design. Numerical simulations have been conducted for MDOF building models equipped with an active control system to demonstrate the stability and control performance of these time‐delay compensation methods. Finally, the stability and performance of the phase shift method, that is well‐known in civil engineering applications, have also been critically evaluated through numerical simulations. Copyright © 2000 John Wiley & Sons, Ltd.     

Compensation of actuator delay and dynamics for real‐time hybrid structural simulation

Compensation of delay and dynamic response of servo‐hydraulic actuators is critical for stability and accuracy of hybrid experimental and numerical simulations of seismic response of structures. In this study, current procedures for compensation of actuator delay are examined and improved procedures are proposed to minimize experimental errors. The new procedures require little or no a priori information about the behavior of the test specimen or the input excitation. First, a simple approach is introduced for rapid online estimation of system delay and actuator command gain, thus capturing the variability of system response through a simulation. Second, an extrapolation procedure for delay compensation, based on the same kinematics equations used in numerical integration procedures is examined. Simulations using the proposed procedures indicate a reduction in high‐frequency noise in force measurements that can minimize the excitation of high‐frequency modes. To further verify the effectiveness of the compensation procedures, the artificial energy added to a hybrid simulation as a result of actuator tracking errors is measured and used for demonstrating the improved accuracy in the simulations. Copyright © 2007 John Wiley & Sons, Ltd.     

Dual compensation strategy for real‐time hybrid testing

Real‐time hybrid testing is an experimental technique for evaluating the dynamic responses of structural systems under seismic loading. Servo‐hydraulic actuators, by nature, induce inevitable time delay between the command and the achieved displacements. This delay would lead to incorrect test results and even cause instability of the system; therefore, delay compensation is critical for stability and accuracy of hybrid simulations of structural dynamic response. In this paper, a dual delay compensation strategy is proposed by a combination of a phase lead compensator and a restoring force compensator. An outer‐loop feed‐forward phase lead compensator is derived by introducing the inverse model in the z domain. The adaptive law based on the gradient algorithm is used to estimate the system delay in the format of parametric model during the test. It is shown mathematically that the parameter in the delay estimator is guaranteed to converge. The restoring force compensator is adopted to improve the accuracy of experimental results especially when the structure is subjected to high frequency excitations. Finally, analytical simulations of an inelastic SDOF structure are conducted to investigate the feasibility of the proposed strategy. The accuracy of the dual compensation strategy is demonstrated through several shaking table tests. Copyright © 2012 John Wiley & Sons, Ltd.     

Real-time hybrid experimental system with actuator delay compensation and its application to a piping system with energy absorber

A real-time hybrid experimental method, in which output from an actuator-excited vibration experiment and response calculation are combined on-line and conducted simultaneously in real time, is being developed as a new seismic experimental method for structural systems. In real-time hybrid experiments, however, there is an inevitable actuator-response delay, which has an effect equivalent to negative damping. To solve this problem, a real-time hybrid experimental system (including an actuator-delay compensation method) was developed. And seismic experiments were conducted in order to demonstrate the advantages of this system. Experimental results obtained using the developed hybrid experimental system were compared with exact results obtained using shaking-table experiments, and it was found that the two experimental methods gave almost identical results. It can therefore be concluded that the structural response can be obtained precisely by using the developed hybrid experimental system. Comparison of these experiments showed the advantages of the hybrid experiments; that is, they are simple and economical. This is because the hybrid experiment requires only a small structure as the excitation model, while a shaking-table experiment must consider the whole structural system. Copyright © 1999 John Wiley & Sons, Ltd.     

Adaptive time series compensator for delay compensation of servo‐hydraulic actuator systems for real‐time hybrid simulation

Hydraulic actuators are typically used in a real‐time hybrid simulation to impose displacements to a test structure (also known as the experimental substructure). It is imperative that good actuator control is achieved in the real‐time hybrid simulation to minimize actuator delay that leads to incorrect simulation results. The inherent nonlinearity of an actuator as well as any nonlinear response of the experimental substructure can result in an amplitude‐dependent behavior of the servo‐hydraulic system, making it challenging to accurately control the actuator. To achieve improved control of a servo‐hydraulic system with nonlinearities, an adaptive actuator compensation scheme called the adaptive time series (ATS) compensator is developed. The ATS compensator continuously updates the coefficients of the system transfer function during a real‐time hybrid simulation using online real‐time linear regression analysis. Unlike most existing adaptive methods, the system identification procedure of the ATS compensator does not involve user‐defined adaptive gains. Through the online updating of the coefficients of the system transfer function, the ATS compensator can effectively account for the nonlinearity of the combined system, resulting in improved accuracy in actuator control. A comparison of the performance of the ATS compensator with existing linearized compensation methods shows superior results for the ATS compensator for cases involving actuator motions with predefined actuator displacement histories as well as real‐time hybrid simulations. Copyright © 2013 John Wiley & Sons, Ltd.     

Improving the inverse compensation method for real‐time hybrid simulation through a dual compensation scheme

Real‐time hybrid simulation combines experimental testing of physical substructure(s) and numerical simulation of analytical substructure(s), and thus enables the complete structural system to be considered during an experiment. Servo‐hydraulic actuators are typically used to apply the command displacements to the physical substructure(s). Inaccuracy and instability can occur during a real‐time hybrid simulation if the actuator delay due to servo‐hydraulic dynamics is not properly compensated. Inverse compensation is a means to negate actuator delay due to inherent servo‐hydraulic actuator dynamics during a real‐time hybrid simulation. The success of inverse compensation requires the use of a known accurate value for the actuator delay. The actual actuator delay however may not be known before the simulation. An estimation based on previous experience has to be used, possibly leading to inaccurate experimental results. This paper presents a dual compensation scheme to improve the performance of the inverse compensation method when an inaccurately estimated actuator delay is used in the method. The dual compensation scheme modifies the predicted displacement from the inverse compensation procedure using the actuator tracking error. Frequency response analysis shows that the dual compensation scheme enables the inverse compensation method to compensate for actuator delay over a range of frequencies when an inaccurately estimated actuator delay is utilized. Real‐time hybrid simulations of a single‐degree‐of‐freedom system with an elastomeric damper are conducted to experimentally demonstrate the effectiveness of the dual compensation scheme. Exceptional experimental results are shown to be achieved using the dual compensation scheme without the knowledge of the actual actuator delay a priori. Copyright © 2009 John Wiley & Sons, Ltd.     

结构主动控制系统时间滞后测量与补偿方法

本文研究了结构主动控制系统时间滞后产生的原因,利用作者建立的结构主动控制系统进行了系统时间滞后测量方法的研究,测量得到了该系统时间滞后的具体数值,在此基础上,研究了时间滞后对控制系统的影响,提出了结构主动控制系统时间滞后的三种补偿,即移相法,泰勒级数展开法和预估状态向量法,通过主动控制试验证了时间滞后补偿方法的有效性。     

Actuator dynamics compensation based on upper bound delay for real‐time hybrid simulation

Real‐time hybrid simulation represents a powerful technique capable of evaluating the structural dynamic performance by combining the physical simulation of a complex and rate‐dependent portion of a structure with the numerical simulation of the remaining portion of the same structure. Initially, this paper shows how the stability of real‐time hybrid simulation with time delay depends both on compensation techniques and on time integration methods. In particular, even when time delay is exactly known, some combinations of numerical integration and displacement prediction schemes may reduce the response stability with conventional compensation methods and lead to unconditional instability in the worst cases. Therefore, to deal with the inaccuracy of prediction and the uncertainty of delay estimation, a nearly exact compensation scheme is proposed, in which the displacement is compensated by means of an upper bound delay and the desired displacement is picked out by an optimal process. Finally, the advantages of the proposed scheme over conventional delay compensation techniques are shown through numerical simulation and actual tests. Copyright © 2013 John Wiley & Sons, Ltd.