Damping Capacity and Seismic Performance of a Torsional Metallic Damper Using a Displacement Amplification Mechanism

Metallic dampers with plastic energy dissipation are often used in the seismic protection of civil structures. However, conventional metallic dampers cannot provide adequate energy dissipation capacity due to the small displacement vibrations. This paper proposed a torsional metallic damper to improve energy dissipation performance. The proposed damper utilized ball screw devices to amplify plastic deformation, which can excessively enhance its damping capacity. First, the axial tension and pure torsion experiments were conducted to evaluate the energy dissipation capacity of solid aluminum round rods under different loads. The torsional tests of three different sections of aluminum rods were carried out to explore the optimal section of torsional energy consumption. The results showed that aluminum 1060 exhibits good plastic properties under pure torsion and the solid aluminum rod had the best energy dissipation capacity among the three test specimens. Second, the dynamic theoretical model of the proposed damper was established and verified by experiment results. The influence of the diameter and length of the aluminum rod and the lead of the ball screw on the energy dissipation performance of the damper was also analyzed. Finally, a cable-stayed bridge was numerically modeled to verify the damping performance of the proposed damper for longitudinal seismic control, which indicates that the displacement of the bridge at the girder end and tower top is significantly reduced with the proposed damper compared to that without the damper. In general, the displacement amplification mechanism of the proposed damper can increase the damping capacity, and the optimal parameters of the damper designed from one certain earthquake wave are also effective for response reduction under other waves.