Regenerative hybrid electrodynamic damper for stay cables

Abstract

Although cable supported bridge construction has greatly increased in popularity over recent years with the development of bridge design and construction technology, problems of serviceability and the maintenance of dampers due to cable vibration have been continuously raised. Therefore, research on electromagnetic dampers that can reduce maintenance costs by monitoring vibration through semi-permanent drive characteristics, attenuation function through semi-active control, and energy harvest function through self-power generation is actively underway. In this study, a new type of regenerative hybrid electrodynamic damper was proposed for reducing stay cable vibration. The damping and energy harvesting performance of the proposed damper was analyzed, and the applicability of the integrated monitoring system was examined. To propose a new type of damper, the numerical analysis of the mathematical model and the characteristic tests of the dampers including the eddy current type electromagnetic damper were carried out, and a finite element model was established based on the main design variables derived. Through electromagnetic finite element analysis, the electromagnetic and physical characteristics and dynamic hysteresis of the proposed damper were analyzed. Based on the experimental results, validity of the finite element model was verified and an optimization analysis was performed to improve damping density. The prototype of the proposed damper and cable exciter were fabricated, and the damping performance was evaluated by performing cable vibration test and analyzing the response. The damping and induced current changes according to the external resistance connected to the damper were analyzed to examine the semi-active control utilization and energy harvesting performance. The analysis results confirm that the proposed new type of regenerative hybrid electrodynamic damper showed enhanced damping and energy harvesting than the electromagnetic dampers represented by coil type. The feasibility of building an integrated system that can simultaneously perform damping and vibration monitoring was confirmed.