Abstract
To avoid the failure under the longitudinal, shear, and mixed wave from earthquake, an archetypal vibration isolator based on a smooth and discontinuous (SD) oscillator is proposed. This model comprises a lumped mass mounted by a vertical spring and a horizontal elastic continuum, which separately provides positive and the negative stiffness forming the stable quasi-zero stiffness (SQZS) in all vertical and horizontal directions. The equation of motion is formulated by employing the Lagrange equation, and the SQZS condition is obtained by optimizing the geometrical parameters of the system. The analysis shows that the system admits remarkable performance in vibration isolation with low resonant frequency and a large stroke of SQZS interval. The results also demonstrate the system has improved aseismic behaviour under the complex excitation of seismic wave significantly.
Highlights
This work is motivated by the increasing concern for the seismic hazard resulted from the low-frequency seismic waves [1,2,3,4], which can be equivalent to longitudinal and tangential motion waves
We have proposed an archetypal vibration isolator, based on smooth and discontinuous (SD) oscillator, with stable quasi-zero stiffness (SQZS) in vertical and all horizontal directions to suppress the destruction caused by seismic waves
It is interesting that a fixed point is found for the proposed SQZS which is much lower than the linear one, showing the remarkable performance in vibration isolation with low resonant frequency and a large stroke of SQZS interval
Summary
This work is motivated by the increasing concern for the seismic hazard resulted from the low-frequency seismic waves [1,2,3,4], which can be equivalent to longitudinal and tangential motion waves. Attentions have been made on nonlinear lowfrequency vibration isolation structure, which significantly improves the isolation performance [11,12,13,14,15,16]. These works mainly focus on vertical damage using stable quasi-zero stiffness (SQZS) system with single degree-of-freedom (DOF), which is invalid for horizontal direction. We propose an archetypal vibration isolator with SQZS in multiple directions based on the SD oscillator to protect structure failure from the complex waves vertically and horizontally. The evaluations are given for the system under the real earthquake ground acceleration record to get the mechanism for structure failure of the system, which enable the scheme to ensure the safety
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