Optimal design of multiple annular tuned liquid dampers for seismic reduction of 1,100-kV composite bushing

Abstract

It is of great significance to perform seismic mitigation for the 1,100-kV composite bushings because they are vulnerable to damage during earthquakes. In this paper, a new design process of multiple tuned liquid dampers (MTLDs), utilizing the displacement transfer function curves and the equivalent mechanical model of annular tuned liquid damper (ATLD), is proposed for seismic reduction of the 1,100-kV composite bushing. At first, the equivalent mechanical model of ATLD is derived based on the linear wave theory. The effects of the radius ratio and the liquid-filled depth ratio on the equivalent sloshing mass are discussed. The accuracy of the equivalent mechanical model is also verified by comparing the results with those from the Housner's model and the finite element model. And then, the transfer functions of the structure with MATLD attached are formulated in the frequency domain. The parameters, including the frequency ratio, the mass ratio, and the damping ratio, that influence the transfer function curves are also investigated. Based on these transfer function curves, the new design process of MATLD is presented. Combining with the equivalent mechanical model of ATLD, a dynamic analysis of the bushing equipped with MATLD in the dome is performed under the real earthquake records. It is concluded that the MATLD performs better than the ATLD and the bushing equipped with 5ATLD in the dome is the optimal design for seismic reduction.