Investigating the analytical and experimental performance of a pure torsional yielding damper.

A new yielding damper with pure torsional mechanism is introduced and investigated in this paper. Story shear force is transferred to the proposed device using special details to produce pure torsion without shear force and bending moment in the damper pipes. Hence, energy dissipation capacity of damper material could be efficiently used. Some relationships for structural characteristics of the proposed damper including initial stiffness, yielding and ultimate strength and load-displacement relation, are derived analytically. This is done by assuming a bi-linear curve for steel material considering its strain hardening. Ten specimens of this pure torsional damper were tested under cyclic loading. The hysteresis curves indicate a stable and well-shaped cyclic behavior. Results also show high energy absorption capacity and ductility for this damper. Widespread yielding and uniform stress distribution across the entire thickness of the pipe wall of the damper results in high equivalent viscous damping ratio from 38% to 48%. The structural characteristics of the tested specimens were compared with analytical relationships. In addition, a parametric study was conducted based on the analytical equations. • The hysteretic behavior of the proposed pure torsional damper (PTD) was stable in experimental tests. • PTD has high energy absorption capacity. • Analytical relationships obtained by considering bi-linear behavior for steel estimate experimental results accurately. • These relationships could be used with proper accuracy for designing PTDs. • Equivalent viscous damping ratio of 38–48% was observed for PTDs. [ABSTRACT FROM AUTHOR]