Abstract

A simplified methodology is rigorously studied in this article to analyze the modal properties of base-isolated high-rise structures with dynamic soil–structure interaction being considered. The proposed methodology is developed based on a more reasonable 2-degree-of-freedom model and the existing simplified methodology which is only applicable for non-isolated structures. The base-isolated structure model with 2 degrees of freedom is supported by swaying and rocking springs and by the corresponding dashpots. Rigorous mathematical derivation is performed, and closed-form formulas of natural periods, modes, and modal damping ratios are derived. Furthermore, the overall accuracy of the proposed methodology was checked against the results of the rigorously derived complex eigenvalue approach proposed by Constantinou and Kneifati. A parametric study is also conducted on the soil–structure interaction effects of base-isolated structures, which indicates that tall and slender structures with stiff isolation systems are more affected by soil–structure interaction effects in comparison to flexible superstructures. The proposed method provides a feasible way to evaluate the soil–structure interaction effects of base-isolated structures efficiently during the schematic design phase.

Highlights

  • As a new kind of anti-seismic approach, a base isolation system has been widely adopted in different structures, and numerous engineering applications have recently verified that this system is effective for protecting structures from earthquake motions.[1]

  • This study presents a simplified reasonable 2-developed an equivalent 2degree-of-freedom (DOF) model for the base-isolated high-rise structures by characterizing the seismic property and considering the soil– structure interaction (SSI) effects

  • In order to investigate the SSI effects of a base-isolated high-rise structure, a more rational model was adopted and a new simplified method has been developed for the evaluation of dynamic characteristic parameters

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Summary

Introduction

As a new kind of anti-seismic approach, a base isolation system has been widely adopted in different structures, and numerous engineering applications have recently verified that this system is effective for protecting structures from earthquake motions.[1]. Keywords Soil–structure interaction, base-isolated structure, large aspect ratio, modal properties

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