抗震拟动力试验技术研究

在全面论述拟动力试验技术的基础上，提出了大刚度多自由度钢筋混凝土结构和砌体结构的拟动力试验技术新方法，即以力控制方式为基础的力－位移混合控制方法，这种方法能实现大刚度多自由度钢筋混凝土结构和砌体结构的拟动力试验。     

位移保护下力-控制拟动力试验方法的原理

本文提出了大刚度多自由度钢筋混凝土结构和砌体结构的拟动力试验技术新方法，即以力控制方式为基础的力－位移混合控制方法。这种新方法能实现大刚度多自由度钢筋混凝土结构和砌体结构的拟动力试验。     

大刚度结构力控制拟动力实验方法

由于受到拟动力实验加载系统和量测系统精度限制，对大刚度结构采用位移控制的拟动力实验方法已失效，本文提出了适用于大风度结构的力控制拟动力试验方法，阐述了方法的原理与步骤，并用实验实例验证了该方法是可行的和可靠的。     

足尺钢框架振动台试验及动力弹塑性数值模拟

本文通过有限元分析程序OpenSees对一足尺四层钢框架结构进行静力及动力弹塑性分析,结构构件采用自由度较少的纤维模型模拟。在振动台试验之前,预测足尺钢框架结构连续在小震、中震及大震作用下的响应,将预测分析结果与振动台试验结果进行对比,结果显示该数值模拟方法能很好地反映结构的弹塑性行为及破坏机制,准确预测结构的地震响应及大震下结构倒塌时间。这进一步说明基于纤维模型的整体结构弹塑性分析方法,由于自由度数少,适用于整体结构抗震分析。     

等效力控制方法及其在混合试验中的应用

对于大型复杂结构的实时(拟动力)子结构试验,更适宜用无条件稳定的逐步积分方法。隐式逐步积分方法通常是无条件稳定的,然而需要复杂耗时的迭代求解非线性方法。为了避免迭代过程,等效力控制方法用反馈控制求解非线性方程,使隐式逐步积分方法在实时子结构试验中的应用成为可能。本文首先以平均加速度法为例介绍等效力控制方法的原理、关键参数的选取;然后介绍基于等效力控制的能量守恒子结构试验方法和隐式中点法;最后介绍这些方法在以防屈曲支撑阻尼器为试件的单自由度简化结构、以磁流变阻尼器为试件的海洋平台结构的实时子结构试验,以及装配式钢筋混凝土剪力墙结构和框支配筋砌块短肢剪力墙结构拟动力试验中的应用。研究结果表明:这三种等效力控制方法都具有很好的精度,等效力控制方法相对于中心差分法具有更好的稳定性。     

配重不足时的动力试验模型与原型相似关系问题的探讨

本文分析了动力方程法和参数的量纲分析法的关系。指出采用量纲分析法时正确选择基本参数的重要性。文中用两种方法推导了不同配重条件下,模型与原型的动力相似关系,并且提出了在结构进入弹塑性阶段后,应如何根据得出的相似关系来分析原型的动力性能。为解决振动台试验时配重不足条件下,如何根据试验结果正确地推算原型结构的抗震性能提供了一种可靠的定量方法。文中以两个1/4比例八层砌体结构房屋模型的振动台试验结果和足尺模型的动力分析结果验证了本文给出的动力相似关系的正确性。     

单层结构远程协同拟动力试验平台开发

基于网络通讯平台NetSLab,采用Visual Basic语言开发了一个标准化的开放式单层结构远程协同拟动力试验平台NetSLab-SDOF,它由控制中心、真实试验机、虚拟试验机和远程观察器4个模块组成,并通过互联网传输试验控制信号和反馈数据。该平台可以使不同的结构实验室联合进行结构拟动力试验,同时还提供远程用户同步观察试验并获取试验数据的功能。通过桥梁结构的真实拟动力试验及数值模拟试验和网络速度测试,验证了NetSLab-SDOF试验平台的有效性。     

基于钢筋混凝土足尺柱拟静力试验的离线模型更新混合试验方法

离线模型更新混合试验对构件拟静力数据进行恢复力模型参数识别,并更新数值子结构中相应构件的模型参数来提高混合试验精度,但该方法尚缺少真实试验的验证。本文基于课题组开展的足尺RC柱拟静力试验,取恢复力模型为集中塑性铰Ibarra-Medina-Krawinkler（IMK）模型,进行框架结构离线模型更新混合试验研究。结果表明,当物理子结构取为RC足尺柱时,离线模型更新混合试验能获得接近于真实试验情况下结构的地震响应,从而对该方法的有效性进行了试验验证。利用IMK经验公式,将真实试验模型参数识别值按轴压比进行对照修正,应用于不同层数的框架结构地震响应模拟,实现了试验数据的重复利用。     

基于振动台的动力子结构试验界面反力获取方法

基于振动台的实时子结构动力试验是一种新型的结构动力试验方法.该试验方法引入了“子结构”这一概念,不仅减小了常规振动台试验对于试验规模的限制,而且克服了拟动力子结构试验中无法考虑加载速率影响的问题.由于该试验方法将整体结构拆分为数值子结构和物理子结构两部分,二者之间通过交界面相互作用力实现实时数据交互,以保证子结构体系与...     

子结构技术在结构抗震试验研究中的应用

根据结构试验理论和实验设备的特征,阐述了结构抗震试验的特点及发展,重点分析了子结构拟动力试验方法的原理、数值积分算法、加载方式和误差控制;振动台子结构试验的原理、研究成果;实时子结构的原理和时滞等混合试验方法的基本理论,以及大型通用有限元软件及远程协同试验方法在混合试验中的应用。基于各种试验方法的优势与发展,总结出混合试验技术未来的发展方向。     

子结构地震模拟振动台混合试验原理与实现

为了解决地震模拟振动台承载能力及台面尺寸对大型结构试验的限制,扩展振动台的功能,本文提出了子结构地震模拟振动台混合试验方法、试验过程及实时数值积分方法,并给出了试验子结构边界条件的两种模拟形式.通过一个简单框架结构的地震模拟振动台试验和子结构混合加载试验验证了该方法的可行性,并指出了该试验方法的主要技术问题.混合试验方法通过子结构技术和振动台试验相结合,解决了目前的地震模拟振动台试验和拟动力试验在设备规模和加载速度上的局限性.     

设有圈梁与构造柱的砌体结构预应力筋抗震加固试验研究

通过对设有圈梁与构造柱的砌体结构采用体外预应力筋加固和未加固模型进行双向拟动力试验,对墙体裂缝开展、结构耗能、结构损伤等指标进行对比分析,探讨体外预应力筋加固对砌体结构抗震能力的影响.试验结果表明:体外预应力筋产生的约束力对限制裂缝开展、防止圈梁与预制楼板的脱空效果明显砌体结构在体外预应力筋加固后的总滞回耗能大于未加固...     

钢筋混凝土框架结构在小震作用下失效相关性的拟动力模型试验研究

通过两榀二层三跨规范钢筋混凝土对称、非对称框架结构模型的拟动力试验,对试件在小震作用截面约束的失效相关性进行了分析,并与文献中的Monte-Carlo随机模拟结果进行了比较,进一步验证了规范钢筋混凝土框架结构在小震作用下失效独立的相关性结论。     

远程协同结构试验方法研究与发展

本文对美国“NEES计划”、欧洲“减轻地震风险的欧洲网络”研究计划、日本E-Defense建设及其远程协同试验、中国台湾地区国家地震工程研究中心ISEE计划和由国家基金委资助的正在进行的重点项目“现代结构拟动力地震模拟协同试验方法与系统”(HQH-NSER)进行了简要介绍,叙述了在远程协同试验研究中的一些关键问题及其应用领域,并对未来的发展趋势作一展望。     

Response of infilled frames using pseudo-dynamic experimentation

An accurate and practical testing technique to study seismic performance of multi-storey infilled frames is formulated. This technique is based on the pseudo-dynamic method which can provide an acceptable approximation of the dynamic performance of structures under the influence of earthquake excitation. The pseudo-dynamic experimental technique is outlined and applied for testing a two-bay, two-storey gravity load designed steel frame infilled with unreinforced concrete block masonry walls. From the discussion of the results, the dynamic performance of the tested structure is assessed. © 1998 John Wiley & Sons, Ltd.     

Pseudo-dynamic testing using conventional testing devices

This paper presents the development of a new type of pseudo-dynamic test system, in which a conventional static jack is utilized for loading. Two of the new hardware devices developed for the system are detailed: a hydraulic pump system that can adjust the rate of oil flow using an inverter motor, and a controller that controls the jack's motion with a displacement feedback signal transmitted from a digital displacement transducer. The unique advantages of the system are summarized as: larger force capacity achieved by the static jack, maximum use of hardware devices available in many existing structural testing laboratories, and flexibility for program development accomplished by separating tasks into multiple PCs. The reliability of the system is calibrated first by a pseudo-dynamic test for an SDOF system and then by a pseudo-dynamic test for a ten-storey building model having hysteretic dampers. For the latter test, substructuring techniques have been incorporated. The accuracy of the results obtained is discussed based upon the capacity of the system to control displacement and comparison with numerical results.     

Adaptive time stepping in pseudo-dynamic testing of earthquake driven structures

The problem of assessing errors in implementing time-marching algorithms in the context of pseudo-dynamic seismic testing of structures is considered. These errors occur in implementing the numerical and experimental steps of the test procedure. The study investigates how a linearized variational equation can be augmented with the governing equation of motion to track the effect of the errors, and, accordingly, adjust the step size of integration adaptively to keep a global error norm within specified limits. The governing augmented equations are integrated using an explicit operator splitting scheme. Additional efforts, in terms of evaluation of the tangent stiffness matrix, are shown to become necessary while modelling the errors. Illustrative examples include numerical studies on a set of nonlinear systems and an experimental study on a geometrically nonlinear two-storied building frame. The experimental results from pseudo-dynamic test are shown to compare reasonably well with pertinent results from an effective force test.     

Full-scale model testing on a ballastless high-speed railway under simulated train moving loads

Model testing in laboratory, as an effective alternative to field measurement, provides valuable data to understand railway׳s dynamic behaviors under train moving loads. This paper presents comprehensive experimental results on track vibration and soil response of a ballastless high-speed railway from a full-scale model testing with simulated train moving loads at various speeds. A portion of a realistic ballastless railway comprising slab track, roadbed, subgrade, and subsoil was constructed in a larger steel box. A computer-controlled sequential loading system was developed to generate equivalent vertical loadings at the track structure for simulating the dynamic excitations due to train׳s movements. Comparisons with the field measurements show that the proposed model testing can accurately reproduce dynamic behaviors of the track structure and underlying soils under train moving loads. The attenuation characteristics of dynamic soil stresses in a ballastless slab track is found to have distinct differences from that in a ballasted track. The model testing results provide better understanding of the influence of dynamic soil–structure interaction and train speed on the response of track structure and soils.     

Pseudo-dynamic tests on masonry residential buildings seismically retrofitted by precast steel reinforced concrete walls

A retrofitting technology using precast steel reinforced concrete (PSRC) panels is developed to improve the seismic performance of old masonry buildings. The PSRC panels are built up as an external PSRC wall system surrounding the existing masonry building. The PSRC walls are well connected to the existing masonry building, which provides enough confinement to effectively improve the ductility, strength, and stiffenss of old masonry structures. The PSRC panels are prefabricated in a factory, significantly reducing the situ work and associated construction time. To demonstrate the feasibility and mechanical effectivenss of the proposed retrofitting system, a full-scale five-story specimen was constructed. The retrofitting process was completed within five weeks with very limited indoor operation. The specimen was then tested in the lateral direction, which could potentially suffer sigifnicant damage in a large earthquake. The technical feasibility, construction workability, and seismic performance were thoroughly demonstrated by a full-scale specimen construction and pseudo-dynamic tests.