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Earthquakes and Structures Volume 27, Number 1, July 2024 , pages 1-15 DOI: https://doi.org/10.12989/eas.2024.27.1.001 |
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Performance enhancement of base-isolated structures on soft foundation based on smart material-inerter synergism |
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Feng Wang, Liyuan Cao and Chunxiang Li
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| Abstract | ||
| In order to enhance the seismic performance of base-isolated structures on soft foundations, the hybrid system of base-isolated system (BIS) and shape memory alloy inerter (SMAI), referred to as BIS+SMAI, is for the first time here proposed. Considering the nonlinear hysteretic relationships of both the isolation layer and SMA, and soil-structure interaction (SSI), the equivalent linearized state space equation is established of the structure-BIS+SMAI system. The displacement variance based on the H2 norm is then formulated for the structure with BIS+SMAI. Employing the particle swarm optimization, the optimization design methodology of BIS+SMAI is presented in the frequency domain. The evolvement rules of BIS+SMAI in the effectiveness, robustness, SMA driving force, inertia force, stroke, and damping enhancement effect are revealed in the frequency domain through changing the inerter-mass ratio, structural height, aspect ratio, and relative stiffness ratio between the soil and structure. Meanwhile, the validation of BIS+SMAI is conducted using real earthquake records. Results demonstrate that BIS+SMAI can effectively reduce the isolation layer displacement. The inerter can significantly increase the hysteretic displacement of SMA and thus enhance its energy dissipation capacity, implying that BIS+SMAI has better effectiveness than BIS+SMA. Although BIS+SMAI and BIS+ tuned inerter damper (TID) have practically the same effectiveness, BIS+SMAI has the lower optimum damping, significantly smaller inertia force, and higher robustness to perturbations of the optimum parameters. Therefore, BIS+SMAI can be used as a more engineering realizable hybrid system for enhancing the performance of base-isolated structures in soft soil areas. | ||
| Key Words | ||
| equivalent linearization; hybrid base isolation; nonlinear; shape memory alloy; soil-structure interaction | ||
| Address | ||
| Department of Civil Engineering, School of Mechanics and Engineering Science, Shanghai University, 333 Nanchen Road, Shanghai, 200444, China | ||