Sustainable Seismic Retrofit Measures for Low-Performing RC Building Structures

Dissipative bracing (DB) systems are among the most sustainable seismic retrofit strategies of reinforced concrete (RC) frame structures, as they allow to minimize the use of materials and the architectural impact, as well as to emphasize the reversibility of the interventions and the reuse of the elements and components by which they are made. A design study on these technologies is offered herein, concerning the application to a 6-storey residential Italian RC frame building, designed in compliance with the 1986 edition of the National Seismic Standards. The masonry infills of the building are explicitly considered in the assessment and retrofit design analyses, modelling them by means of diagonal no-tension struts with multilinear pivot-type hysteretic behaviour. Based on the response evaluated in current conditions, two different DB-based retrofit solutions are proposed, where the bracing system is equipped in one case with Added Damping and Stiffness (ADAS) steel devices, and in the other case with Pressurized Fluid Viscous (PFV) dampers. The characteristics of the examined building, a synthesis of the performance evaluation analysis in current and retrofitted conditions, and a comparison between the protection capacities of the two technologies are presented in the paper.