Development and Implementation of Effective Force Testing: A Method of Seismic Simulation

本研究项目的目标是开发和实施一种测试方法，“有效力测试”（EFT），它可以实时测试大型结构系统在地震荷载下的性能。该方法至少具有两个理想的特征。首先，它允许对大型结构系统进行经济的实时动态测试，这对于受应变率效应影响的结构细节非常重要。其次，它提供了一种在大型结构上测试主动、半主动和被动控制系统的鲁棒性和可靠性的方法。EFT方法提供了补充其他三种主要地震模拟测试方法的能力：振动台、准静态和伪动态。可以测试的结构类型的限制与伪动力测试方法（即固定在实验室地板上的集总质量系统）的要求相似。然而，与伪动态测试方法不同，EFT使用的是力控制算法，而不是位移控制算法。EFT方法可以用于实时地震模拟研究，因为作用于跛行质量结构的有效作用力是已知的。它们是各自楼层质量和地面加速度记录的乘积。因此，有效力与结构响应无关。对线性弹性SDOF系统的EFT方法进行了初步研究，取得了成功；但是发现了与作动器/结构相互作用相关的控制问题。在这个项目中，调查将扩展到系统。该项目将分两个阶段完成。第一阶段包括实验和数值模拟研究，以研究随着测试结构进入非线性行为范围，伺服阀流量需求增加而可能出现的控制问题。控制问题的一个来源可能与伺服阀/执行器的非线性有关，而不是目前在研究者使用的线性模型中考虑到的。为了检测这些问题，将在一个简单的测试结构上进行测试，该测试结构被设计成可重复显示非线性行为。研究的第二阶段将包括在一个复制结构上进行概念验证测试，该结构先前已经在地震模拟器上进行了测试，以比较两种地震模拟技术的结果。整个项目将采用综合的跨学科方法，结合土木工程系的结构测试和分析专业知识，并控制航空航天和力学系的专业知识。东京大学项目的日本合作者将专注于开发一种实时的“在线”测试方法，类似于伪动态测试，包括子结构。本项目得到国家自然科学基金98-36项目“美日城市地震减灾合作研究”的资助。

The objective of this research project is to develop and implement a test method, "Effective Force Testing" (EFT), which enables real-time testing of large-scale structural systems subjected to earthquake loadings. This method has at least two desirable characteristics. First, it permits economical real-time dynamic testing of large-scale structural systems, which is important for structural details affected by strain rate effects. Second, it provides a means of testing the robustness and reliability of active, semi-active, and passive control systems on large-scale structures.The EFT method provides capabilities which complement those of the other three primary types of earthquake simulation test methods: shake table, quasi-static, and pseudodynamic. Restrictions on the type of structures that can be tested are similar to those required by the pseudodynamic test method (i.e. lumped mass systems fixed to the laboratory floor). However, rather than using a displacement control algorithm, as is the case for the pseudo-dynamic test method, EFT uses a force control algorithm. The EFT method can be used to conduct real-time earthquake simulation studies because the effective forces to be applied to the limped mass structure are known a priori. They are the product of the respective story masses and the ground acceleration record. Consequently, the effective forces are independent of structural response.A pilot study conducted on the EFT method on a linear elastic SDOF system was successful; but control problems associated with actuator/structure interaction were discovered. In this project, the investigation will be extended systems.The project will be accomplished in two phases. The first phase consists of experimental and numerical simulation studies to investigate potential control problems expected with increased servovalve flow demands associated with taking a test structure into the nonlinear range of behavior. A source of control problems may be associated with servovalve/actuator nonlinearities not currently accounted for in the linear models used by the investigators. To detect these problems, tests will be conducted on a simple test structure designed to repeatably exhibit nonlinear behavior. The second phase of the research will consist of a proof-of-concept test on a replicate structure, which has been tested previously on an earthquake simulator to compare the results of the two earthquake simulation techniques.An integrated interdisciplinary approach will be used throughout the project, which combines structural testing and analysis expertise from the Department of Civil Engineering faculty, and controls expertise from the Department of Aerospace and Mechanics faculty. Japanese collaborators on the project at University of Tokyo will focus on developing a real-time "on-line" testing method, similar to pseudo-dynamic testing, including substructuring.This project is supported under NSF 98-36, "US-Japan Cooperative Research on Urban Earthquake Disaster Mitigation."