Polynomial friction pendulum isolators (PFPIs) for building floor isolation: An experimental and theoretical study

Published Date
November 2013, Vol.56:970–982, doi:10.1016/j.engstruct.2013.06.016

Author 

• Lyan-Ywan Lu ^a,,
• Tzu-Ying Lee ^b
• Shiang-Yu Juang ^c
• Shih-Wei Yeh ^d

• aDepartment of Construction Engineering, National Kaohsiung First University of Science and Technology, 1 University Road, Yenchao, Kaohsiung 824, Taiwan
• bDepartment of Civil Engineering, National Central University, Jhongli City, Taoyuan County, Taiwan
• cDepartment of Construction Engineering, National Kaohsiung First University of Science and Technology, Taiwan
• dDepartment of Civil Engineering, National Cheng-Kung University, Tainan, Taiwan

Received 19 November 2012. Revised 7 June 2013. Accepted 12 June 2013. Available online 20 July 2013. 

Highlights

• A multi-functional floor isolation system that has dual design objectives is studied.
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  The proposed isolation system consists of variable-stiffness sliding isolators.
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  The sliding surfaces of the isolators are defined by a sixth-order polynomial.
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  A design procedure to determine the isolator design parameters are proposed.
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  The test and numerical results verify the feasibility of the proposed system.

Abstract

Compared to structural base isolation, floor isolation is a more cost-effective and efficient means for seismic protection of vibration-sensitive equipment in a building structure. In this study, a multi-functional floor isolation system (FIS) that consists of several variable-stiffness sliding isolators, called polynomial friction pendulum isolators (PFPIs), is proposed and studied experimentally and numerically. Due to its variable-stiffness nature, the proposed PFPI-FIS is able to achieve multiple design objectives. This paper also demonstrates the procedure to design a prototype PFPI-FIS which meets the desired dual performance objectives for two-level seismic loads. The shaking table tests verify that the prototype system possesses the desired hysteretic property with variable stiffness, and the measured responses match very well with the simulated ones. Moreover, by considering ten ground motions that represent earthquakes with different spectral contents, the seismic responses of the prototype PFPI-FIS under these ground motions with different intensity level are simulated extensively. The simulated results demonstrate that the isolation performance of the PFPI-FIS does comply with the designated dual performance objectives, which yield either acceleration or displacement control depending on the earthquake intensity and isolator drift.

Keywords

Floor isolation

Variable stiffness

Sliding isolation

Friction pendulum

Shaking table test

Multiple objectives

Equipment protection

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