Amplification system for concentrated and distributed energy dissipation devices

Abstract

Recent analytic, experimental, and practical studies are developing energy dissipation devices combined with amplifying mechanisms (AM) to enhance structural behavior. This research presents the theoretical and experimental development of the eccentric lever-arm system (ELAS), a new system generically called amplified added damping (AAD), which is a combination of an AM with one or more dampers capable of supporting large deformations. The proposed AM device is a variant of the well-known lever-arm system. This work is divided in four parts: (1) kinematics of the ELAS and definition of an equivalent AAD; (2) parametric analysis of a linear single-story structure with ELAS; (3) numerical analysis of a multi-degreeof-freedom structure with frictional damping with and without AM; and (4) pseudo-dynamic tests of a full scale asymmetric one story steel structure with and without frictional AAD. Parametric analyses demonstrate that using high-amplification ratios and low supplemental damping could be a good practice . On the other hand, similar to systems without AMs, dissipation efficiency increases conformably with the stiffness of thesecondary structure. As expected, it was observed that deformation was highly concentrated in the flexible edge of the asymmetric test model without damper. Conversely, the structure with frictional AAD clearly showed uniform plane deformation. The implemented AM, which has a large amplifying ratio of alpha= 11, performed with close accordance with numerical simulations and a high mechanical efficiency c=95% using a frictional damper with a very low force capacity.