A Displacement-based Method for the Retrofit of Existing Masonry Structures with ADAS Dampers and External Concrete Walls

This paper addresses a displacement-based method for the design of an energy dissipating system aimed at the seismic upgrading of existing masonry structures. The dissipating system is composed of hysteretic dampers (ADAS) and external concrete walls. The devices are installed within the concrete walls at floor level and are connected to the structure with steel connectors. The design method is based on a simplified model of the overall structural-dissipating system. This model is verified through comparisons with a more refined model. The proposed design procedure is essentially based on the knowledge of the nonlinear static response of the existing structure. The effectiveness of the design method is tested by means of inelastic time-history analyses considering four masonry test structures and different types of hysteretic behaviour and spectrum compatible records. The results of the analyses are then compared with the seismic response expected from design.