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 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. The implemented AM, which has a large amplifying ratio of˛ 11, performed with close accordance with numerical simulations and a high mechanical efficiency . 95%/ using a frictional damper with a very low force capacity.[1, 2]; and (ii)connecting the beam of the building and the damper though an auxiliary V-shaped structure ('chevron'), where the damper works horizontally. These configurations are shown in Figure 1 (a and b), where they are identified as diagonal and chevron systems, respectively.Both configurations are generally appropriate for flexible buildings. However, stiff structures such as buildings with reinforced-concrete shear walls obstruct the implementation of energy dissipation systems because inter-story drifts generated under seismic excitations can not produce enough deformation (and energy dissipation force) in the dampers. To overcome this problem, various amplifying mechanisms (AM) have been proposed [3,4], including the Toggle Brace Damper (TBD) [1, 5-7], scissor-jack damper [8], lever-arm systems (LASs) such as the DREAMY system of Taisei Corporation [9, 10], hydraulic amplification devices [11], seesaw-damper system [12][13][14], and amplification systems based on pinions with different diameters [15]. Figure 1 schematically shows some of these systems along with the traditional chevron and diagonal systems.It is important to note that the efficiency of energy dissipation devices depends on the stiffness of the elements designed to transmit deformation (inter-story drift) from the main structure to the energy dissipation devices (henceforth, named secondary structure or secondary system). Because both secondary structure ...
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