Seismic control of two adjacent structures connected by an energy dissipation enhanced torsional eddy current damper: Optimum design and performance analysis

As urban space becomes increasingly constrained, structural spacing is often minimized within code-permitted limits, making closely spaced adjacent structures increasingly common. Under earthquakes, however, large relative motions between adjacent structures can increase the potential risk of pounding when the available clearance is insufficient. To reduce the relative displacement associated with this potential risk, this study investigates the damping characteristics, optimal design, and seismic performance of an energy dissipation enhanced torsional eddy current damper (EDE-TECD) for adjacent structures. Firstly, the damping coefficient estimation formula for the torsional eddy current damper is derived from electromagnetic theory, and validated using the finite element model and the prototype. Subsequently, the simplified equation of motion of the adjacent structures equipped with the EDE-TECD is established. Based on the numerical search methods, the optimal parameters of adjacent structures at different frequency ratios and mass ratios are obtained. Next, the vibration reduction performance of adjacent structures with either the EDE-TECD or traditional linear viscous damper is compared. Finally, the effects of EDE-TECD equivalent damping ratio deviation and structural stiffness degradation on the vibration reduction performance of the adjacent structures are investigated. The results show that the proposed damping coefficient estimation formula agrees well with the finite element results over the considered operating speed range, and the EDE-TECD can be reasonably represented by an equivalent linear viscous damping model within this range. Increasing the inertial mass does not always favor improving the smaller modal damping ratio. The optimized EDE-TECD achieves an average reduction of 68.5% in the peak relative displacement of the two adjacent structures compared with the uncontrolled case, which is 6.5% higher than the average reduction achieved by the conventional linear viscous damper. Moreover, the results indicate that the EDE-TECD maintains considerable vibration reduction performance under EDE-TECD equivalent damping ratio deviation and structural stiffness degradation.