Overturning of Retrofitted Rocking Structures under Pulse-Type Excitations
Publication: Journal of Engineering Mechanics
Volume 138, Issue 8
Abstract
Numerous existing structures exhibit rocking behavior during earthquakes, and there is a continuing need to retrofit these structures to prevent collapse. In addition, while rocking behavior is typically prevented instead of utilized, an increasing number of structures are being designed or retrofitted to allow rocking motion as a means of seismic isolation. This paper investigates the use of viscous damping to limit the rocking motion by characterizing the fundamental behavior of damped rocking structures through analytical modeling. A single rocking block analytical model is used to determine the viscous damping characteristics, which exploit the beneficial aspects of the rocking motion, while dissipating energy and preventing overturning collapse. To clarify the benefits of damping, overturning envelopes for pulse-type ground accelerations are presented and compared with the pertinent envelopes of the free rocking block. A semianalytical solution to the linearized equations of motion enables rapid generation of collapse diagrams for pulse excitations, which provide insight into the overturning mechanisms of the damped rocking block and the sensitivity of the response to the parameters involved. In addition, through solution of the nonlinear equations of motion, bilateral and unilateral linear viscous dampers are shown to provide similar benefit toward preventing overturning, while nonlinear damping is found to provide relatively little and inconsistent benefit with respect to linear damping.
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Acknowledgments
Financial support for this research was provided by the Engineering and Physical Sciences Research Council of the United Kingdom under Grant no. EP/H032657/1.
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Information & Authors
Information
Published In
Journal of Engineering Mechanics
Volume 138 • Issue 8 • August 2012
Pages: 963 - 972
Copyright
© 2012. American Society of Civil Engineers.
History
Received: May 23, 2011
Accepted: Feb 9, 2012
Published online: Feb 11, 2012
Published in print: Aug 1, 2012
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