Seismic Response of a Structure Equipped with an External Viscous Damping System

The aim of this research is to evaluate the effectiveness of a seismic retrofit technique that involves the introduction of energy dissipation devices properly connected to an existing structure through a system of cables and levers, which are employed to amplify total or inter-story drift at device end. One of the main topics related to the introduction of energy dissipation devices, lies in the choice of their optimal setting within the structure to maximize the effectiveness without producing functionality limitations. The achievement of these objectives is, therefore, linked, regardless of the type adopted, to the amount of energy dissipated in each cycle, directly proportional to the displacement magnitude to which the device is subject. Many configurations proposed in the literature and currently adopted in professional practice provide additional dissipation systems variously connected to braces installed inside the structural frame and, therefore, able to exploit the inter-story drift produced by seismic input. The proposed system exploits top displacements of the structure with respect to the foundation level, transferred to the device through a system of cables properly configured and amplified with leverage. This paper represents the first step of the research, in which simple single degree of freedom (SDOF) or two degrees of freedom (2-DOF) models are taken into account to evaluate the effects of the introduction of the proposed system in terms of reducing the seismic demand on the structure, proceeding to a parametric analysis to obtain initial indications for the design of the system in relation to the geometric and inertial characteristics of the original structure.