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Title:Model-based Strategies for Real-time Hybrid Testing
Author(s):Carrion, Juan E.; Spencer, Billie F., Jr.
Subject(s):real-time hybrid testing
pseudodynamic testing
actuator dynamics
delay compensation
model-based compensation
MR damper
semi-active control
Abstract:Experimental testing is an essential tool for understanding how structures respond to extreme events, thus allowing the design and construction of safer structures. Methods currently used to determine the behavior of structural systems subjected to dynamic loading are quasi-static, shaking-table, and hybrid (or pseudodynamic) testing. In hybrid testing, the dynamic response of the structure is calculated numerically on a computer, and then the restoring forces from the structure are obtained by applying the calculated displacements to a test specimen. The combination of physical testing with numerical simulation provided by hybrid testing facilitates accurate and efficient testing of large and complex structural systems. Because conventional hybrid testing is executed at slow speeds, the method is not applicable for structures with rate-dependent components (for example, devices associated with vibration control). To allow testing of such structures, researchers have proposed a variation of the method called real-time hybrid testing in which the experiment is executed in real time. Real-time hybrid testing is challenging because it requires guaranteed execution of each testing cycle within a fixed, small increment of time (typically less than 10 msec). Furthermore, unless appropriate compensation for time delays (from communication and computing time) and actuator dynamics is implemented, stability problems are likely to occur during the experiment. Traditionally, researchers have lumped the effects of time delays and actuator dynamics together and treated them as a constant time delay; techniques were then developed to compensate for this total time delay. However, these techniques only perform well when the delay is small compared to the fundamental period of the structure. The focus of this report is to develop an approach for real-time hybrid testing that uses model-based methods to compensate for time delays and actuator dynamics and combines fast hardware and software (for high-speed computations and communication) with high performance hydraulic components. The studies presented in this report extend the capabilities of real-time hybrid testing by facilitating accurate testing of structural systems with larger natural frequencies (e.g., stiff structures or multi-degree-of-freedom systems) and handling larger delays/lags which are typically associated with actuators with high force capacity. Furthermore, these studies demonstrate that real-time hybrid testing is an effective and practical technique to evaluate the response of structures incorporating devices for passive and semiactive structural control.
Issue Date:2007-12
Publisher:Newmark Structural Engineering Laboratory. University of Illinois at Urbana-Champaign.
Series/Report:Newmark Structural Engineering Laboratory Report Series 006
Genre:Technical Report
Publication Status:published or submitted for publication
Rights Information:Copyright held by the authors. All rights reserved.
Date Available in IDEALS:2008-02-19

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