Retrofit of Existing Reinforced Concrete (RC) Buildings: Steel vs. RC Exoskeletons

The existing building stock is largely made up of reinforced concrete (RC) buildings, constructed between the post-World War II period and 1981, and mostly consists of buildings constructed very quickly to meet the great housing demand of this period, and buildings that do not adhere to anti-seismic and energy regulations. Today, after more than fifty years, these buildings have reached the end of their useful life cycle and their maintenance is not sustainable, presenting a series of structural, energy and architectural problems and criticalities. The myriad of possible retrofit interventions currently available for these RC structures drastically reduces when the main requirement for interventions is to avoid operational interruptions to buildings. In this case, an additive structure, operating exclusively from the outside as an exoskeleton, is typically used for achieving appropriate retrofit. In this paper, two solutions are proposed and addressed for the retrofit of an existing RC building in Italy, one through the application of a steel exoskeleton and the other through the application of an RC exoskeleton system. A set of push-over (PO) analyses is carried out to define the performance point of both the original and combined systems. The comparative results of these solutions are then discussed.