A sustainable solution for the seismic strengthening of RC existing buildings through the HPDF system (HPDF): A case study

The large number of existing buildings for which seismic rehabilitation interventions are required highlights the need of sustainable techniques able to reduce costs and downtime. To this purpose, a new strengthening technique named High-Performance Dissipating Frame (HPDF) was developed. It consists of new framed structures applied from the outside thus reducing the impact and relocation needs of tenants. This is even more important for strategic (e.g. hospitals) and other public buildings (e.g. schools) due to the social and economic effects deriving from their interruption of use. HPDF system consists of external precast RC frames (i.e. exoskeletons) rigidly connected to the existing structure and equipped with both shear and flexural damper devices to provide a high dissipation capacity in case of seismic actions and then to protect existing building. In the paper, the HPDF system has been applied to a Reinforced Concrete (RC) school building designed only to gravity loads. After a brief description of the building under study and the HPDF system, the stiffness, strength, and dissipation properties have been determined using an iterative displacement-based design procedure purposely set up. Results show that the considered strengthening technique increases seismic performance of the existing building according to different targets involving both structural and non-structural components, also avoiding any other local intervention.