Seismic strengthening and energy efficiency: Towards an integrated approach for the rehabilitation of existing RC buildings

In Italy, most of the residential buildings (77%) were constructed before 1981, when only 25% of the national territory was classified as seismic. Further, the first provisions addressing thermal performance criteria were introduced in 1991, when about 88% of the existing Italian buildings had already been realized. Therefore, the Italian building stock is characterized by a large deficit in terms of both seismic capacity and thermal insulation. The large number of buildings having inadequate performance, both seismic and thermal, calls for rehabilitation interventions that are based on an integrated and sustainability-oriented approach. In the paper, the influence on seismic performance deriving from some retrofitting techniques, generally adopted to enhance the thermal performance of infill walls, has been evaluated. A common residential RC building representative of existing buildings designed only for vertical loads has been studied. The seismic performances have been evaluated through Incremental Dynamic Analyses (IDA). A first comparison is related to a thermal retrofitting intervention made by replacing the existing masonry infill walls with new elements that are able to ensure an adequate thermal protection. Further, a retrofitting intervention based on the "double skin" technique, where new infilled RC frames are added and connected to the existing ones, has been investigated in terms of seismic and thermal performance.