Effects of “reinforced” infilled frames on existing RC buildings

This paper presents some considerations about the role of strengthening interventions involving the solidarization of the infill panels to the RC frame on the seismic retrofitting of existing buildings. Within this context, an appraisal of the actual resulting displacement capacity and of possible alteration induced on the global collapse mechanism and on is provided. Nowadays, it is well-established that infill panels contribute in increasing the overall in-plane resistance to horizontal actions within a variable range of the displacement intervals before they start to degrade. Anyway, in most cases there is also an effect of significant alteration of the overall seismic behaviour and collapse mode, which should be properly taken into account. With reference to a real case study concerning a school building (which was part of a wide vulnerability assessment investigation performed in the Province of Foggia, Italy), an appraisal of the effect of strengthening interventions is here discussed. In particular, the seismic analysis by non linear static procedure has been performed both on the reinforced configuration and on the original structure and critically discussed.