Plastic Input Motion: Transformation for the Response of Yielding Oscillators
Publication: Journal of Engineering Mechanics
Volume 138, Issue 7
Abstract
A transformation method is presented for the response of yielding oscillators to dynamic loading. The method employs a translation in the ordinates and the abscissa of the excitation function by means of a pair of parameters uniquely dependent on the yielding resistance and the vibrational characteristics of the system. By this approach: (1) the differential operator becomes linearlike, with the nonlinearity transferred to the right-hand side; (2) the initial conditions are simplified; and (3) the modified forcing term becomes uniquely associated with the development of plastic deformation. The theory is applied to various yielding oscillators subjected to idealized earthquake pulses, with the modified excitation function termed plastic input motion (PIM). A procedure for applying the method to general waveforms is provided. The coordinates of PIM may be discontinuous and significantly smaller than those of the original excitation function, as a considerable amount of ground acceleration is devoted to overcoming the elastic resistance of the system. The theory can be useful in earthquake engineering by offering a replacement to physical ground motions with system-dependent PIMs for establishing demand indices.
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Acknowledgments
The research at hand was supported by NTUA Basic Research Program Grant No. 65/1720. The writers are grateful for this support. The valuable comments of two anonymous reviewers helped with improving the quality of the paper.
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Information
Published In
Journal of Engineering Mechanics
Volume 138 • Issue 7 • July 2012
Pages: 749 - 760
Copyright
© 2012. American Society of Civil Engineers.
History
Received: Aug 14, 2010
Accepted: Dec 8, 2011
Published online: Dec 12, 2011
Published in print: Jul 1, 2012
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