Optimal design and seismic performance of a velocity-amplified torsional eddy current damper for adjacent structures

Abstract

Abstract Adjacent building clusters with narrow separation gaps are vulnerable to large relative seismic responses and pounding. To address this issue, this study investigates a velocity-amplified torsional eddy current damper (VATECD) for vibration control of adjacent structures. The VATECD combines a torsional eddy current damper with a gear-and-rack mechanism for velocity amplification, thereby increasing the damper angular velocity and improving damping efficiency within a limited installation space. Firstly, finite element models of the torsional and plate eddy current dampers are established in the COMSOL software to compare their damping performance under identical material conditions, and the equivalent damping coefficient of the VATECD is validated by finite element and prototype test results. Secondly, a two-degree-of-freedom adjacent-structure model equipped with the VATECD as a shared damper is developed. Based on the H∞ optimization criterion, the optimal damping coefficient and inertial mass ratio are derived and compared with numerical-search results.Third, the optimized VATECD is evaluated in a ten-story adjacent-frame system under near-field and far-field earthquake records and compared with a traditional TMD. A frequency-detuning sensitivity analysis is further conducted with fixed damper parameters to examine whether the control performance remains stable as the structural frequency decreases. The results show that the VATECD provides higher damping efficiency than the plate ECD and can effectively reduce the displacement response of the target structure compared with conventional TMD. For Structure A, the average displacement reduction ratios are 25.34% and 35.54% under near-field and far-field records, respectively, with a larger average reduction observed for the selected far-field records.