Evaluation in probabilistic terms of behaviour of existing RC structures equipped with friction pendulum devices including presence of masonry infills

The safety assessment of existing structures in areas with a relevant seismic hazard is one of the major topics for engineers since many existing reinforced concrete structures have been realized disregarding seismic design and providing poor detailing in comparison to the current specifications. In this context, the seismic assessment is a primary issue in order to identify the best retrofitting solution with the aim to upgrade the performance level of existing structures. In order to enhance the seismic response of existing RC structures, over the years, the isolation system adopting friction pendulum devices turned out to be one of the most diffused and efficient. The aim of this work is to investigate the effectiveness of the retrofitting intervention using single-concave friction pendulum devices on the seismic performance of an existing 3D reinforced concrete building located in central Italy, which is an area with a high seismic hazard. After the characterization of the geometrical features and material properties according to the “knowledge levels” approach, a non-linear numerical model of the structure has been defined using fiber-based finite elements. 3D non-linear dynamic analyses have been performed considering 21 natural ground motions with the three accelerometric components to assess the seismic response of the building with and without the retrofitting intervention composed of the FP isolators. The influence of infill masonry panels on the overall behaviour of the structure has also been evaluated. The results from the non-linear dynamic analyses have been useful to evaluate the effectiveness of the retrofitting intervention to improve the seismic performance.