Seismic performance analysis and optimization of a re-centring and self-balanced inerter driven by a rhombic linkage

Abstract

This paper proposes a re-centring and self-balanced inerter (RSBI). The rhombic linkage achieves self-balanced of the torque on the screw, which releases the constraints demanded at the end of the screw and reduces the working wastage and cost of the screw. The flywheel's re-centring feature is guaranteed by introducing a self-resetting spring and enhances the stability of the system. More specifically, firstly, the resonance analysis method provides the optimized mounting angle of the RSBI's rhombic linkage. Then, the user-friendly optimal design strategy of the four-parameter inerter system, are derived by applying the fixed-point theory, and the validity of the optimized parameters is verified by parameter and time history analysis. Finally, nonlinear model of the RSBI is performed to account for the nonlinearity due to the variation of the rhombic linkage angle at large working strokes. The nonlinear amplitude frequency response function of the system is obtained using the harmonic balance method and the working stroke of the inerter is classified by comparing it with the linear frequency response function. The device proposed in this paper provides a good control effect on the displacement and acceleration control of the main structure under multiple seismic waves. The nonlinearity of the device is appropriately exploited to almost double the working stroke of the inerter, which can effectively reduce the size of the device.