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A floor slab damper and isolation hybrid system optimized for seismic vibration control

Date

2014

Authors

Engle, Travis J., author
Mahmoud, Hussam N., advisor
Bienkiewicz, Bogusz J., committee member
Clevenger, Caroline M., committee member

Journal Title

Journal ISSN

Volume Title

Abstract

Damage and fatigue to structures due to earthquake loading has cost millions of dollars in repair and reconstruction over the last century. Limited reduction in seismic excitation has been gained through base isolation and tuned mass damping theories. Both theories have limitations that reduce the effectiveness of the system. Getting around these limitations is necessary to accomplish the goals of the study. An innovative design utilizing aspects of both isolation and tuned mass damping is developed by allowing the floor slabs of the structure to displace relative to the frame of the structure. Equations of motion are developed to model this unique system. This system is then optimized and the efficiency of the design is assessed. The reduction of this response over a range of frequencies is the goal of this optimization and thesis. Vibration control is achieved in this system by attempting to remove the mass of the floor slabs from the inertia of the system. When excited, the structure moves while the slabs remain stationary. This greatly reduces the stress on the frame. In this way, the design is a friction isolation and damping hybrid system. The relative motion between the frame and the slab has to be controlled. To control its displacement, the slab is supported by a curved support and bumpers are added. These additions utilize aspects of translational and pendulum tuned mass damper systems and force the slab back to its original location after excitation. This system imitates multi-tuned mass damper systems as well by utilizing multiple floor slabs on multiple stories. Because of the large mass of the floor slabs the system is more effective than any of the standard tuned mass damper systems. The system is optimized for its total response over a range of frequencies compared to a standard composite structure over those same frequencies by adjusting the combination of stories that are activated, the radius of curvature of the slab support, the stiffness of the bumpers, and the coefficient of friction of the contact surface between the support and slab. The response is a normalized multi-objective optimization of the acceleration, global drift, interstory drift, and relative slab drift. The optimized structures can be tested by real seismic records to demonstrate their effectiveness.

Description

2014 Summer.
Includes bibliographical references.

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Subject

isolated floor slab
earthquake response
optimization
tuned mass damper
vibration control
mass ratio

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