DISPLACEMENT-TYPE METALLIC DAMPER BASED ON PURE TORSIONAL ENERGY DISSIPATION OF SINGLE TUBE: THEORY AND EXPERIMENT

This paper presents the design of a displacement-type metal damper that utilizes torsional yield energy dissipation. The damper features a diamond-shaped configuration, employing a spatially asymmetric structure to achieve pure torsional energy dissipation through a single circular tube. When relative linear displacements occur at both ends of the damper, equal and opposite torques are generated at the extremities of the metal tube; once it enters the plastic deformation stage, energy dissipation commences, resulting in corresponding damping forces at both ends. The fundamental mechanical properties of this damper are thoroughly analyzed, and theoretical expressions for initial stiffness and yield load are derived based on bilinear elasto-plastic assumptions while accounting for linkage structures and connection stiffness effects. Additionally, an analysis of geometric large deformations is conducted to evaluate the lateral unbalance coefficient of the damper, demonstrating its capability to maintain equilibrium over an extensive range. A prototype diamond-shaped metal damper with a yield load capacity of 16 tons has been manufactured according to these theoretical expressions and is designed for displacements up to ±40 mm. Its mechanical performance and