Eccentric Lever Arm Amplification System for Frictional Energy Dissipation Devices

Abstract eng:
Recent analytic, experimental, and practical studies are developing energy dissipation devices combined with amplifying mechanisms (AM) to enhance the seismic perfomance of structures with small inter-story deformations. This research presents the theoretical and experimental development of the Eccentric Lever-Arm System (ELAS), a new system which is a combination of an AM with one or more dampers capable of supporting large deformations. This work is divided in four parts: (1) kinematics of the ELAS and definition of an equivalent system without AM; (2) parametric analysis of a linear single-story structure with ELAS; (3) numerical analysis of a stiff multi-degree of-freedom structure with two types of frictional dampers; and (4) pseudo-dynamic tests of a full scale asymmetric one story steel structure with and without frictional dampers. Parametric analyses demonstrate that using high amplification ratios and low supplemental damping could be a very good practice . On the other hand, similar to systems without AMs, dissipation efficiency increases conformably with the stiffness of the secondary 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 (i.e. tosional balance). The implemented AM, which has a large amplifying ratio of 11, performed with close accordance with numerical simulations.

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