Identification of the Mechanical Subsystem of the NEES-UCSD Shake Table by a Least-Squares Approach
Publication: Journal of Engineering Mechanics
Volume 134, Issue 1
Abstract
A least-squares method is used to determine the fundamental parameters of a simple mathematical model for the mechanical subsystem of the NEES-UCSD large high performance outdoor shaking table. The parameters identified include the effective horizontal mass, the effective horizontal stiffness, and the coefficient of the classical Coulomb friction and viscous damping elements representing the various dissipative forces in the system. The values obtained for these parameters are validated by comparisons with previous results based on an alternative identification method applicable only to periodic tests and by comparisons with experimental data obtained during earthquake simulation tests and harmonic steady-state tests. The proposed identification approach works well for periodic sinusoidal and triangular tests, earthquake simulation tests, and white noise tests with table root mean square above 10% of gravity.
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Acknowledgments
This work was supported by the National Science Foundation through the NEES program, Grant No. NSFCMS-0217293; the Englekirk Center Board of Directors and NEESinc through a NEES facility enhancement project, and Lawrence National Laboratory (with Dr. Dave McCallen as research manager). These sources of support are gratefully acknowledged. The writers want to thank Prof. José Restrepo (U.C. San Diego), Prof. Tomaso Trombetti (University of Bologna, Italy) for their significant contributions during the shake-down and characterization tests that produced the data used in this study. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the writers, and do not necessarily reflect those of the sponsors.
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© 2008 ASCE.
History
Received: Feb 9, 2007
Accepted: May 30, 2007
Published online: Jan 1, 2008
Published in print: Jan 2008
Notes
Note. Associate Editor: Lambros S. Katafygiotis
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