Alternative techniques and approaches for improving the seismic performance of masonry infills

This doctoral dissertation aims to report on the research work carried out in the field of alternative techniques and approaches for improving the seismic performance of masonry infills. An aspect often overlooked in the design and/or verification of Reinforced Concrete (RC) frame buildings it is the one related to the so-called "non-structural" elements, that are elements without a main structural function, but capable of causing damage to things and people during the seismic action. A typical example of non-structural elements are the external infills of RC frame buildings, which often have masses and stiffnesses able to significantly modify the behavior and response of the structure during the seismic action. Typically, the UnReinforced Masonry (URM) infill walls are made of single or double facing hollow bricks placed inside the meshes of RC frames. The main damage mechanisms observed in URM infill walls during seismic events include in the plane (IP) or out of the plane (OOP) damage mechanisms, both characterized by degradation of strength, stiffness and low energy dissipation. In this doctoral dissertation, the analysis of the influence of the in-plane and out-of-plane behavior of UnReinforced Masonry infill walls on global seismic performances of different RC frame buildings is presented. The research mainly focuses on: i) numerical investigation of the in- plane / out-of-plane interaction in order to evaluate its entity and severity pointing out the correct description of the damage scenarios; ii) identification of alternative intervention solutions, aimed at mitigating the phenomenon of overturning of the infill panels; iii) estimate of the expected economic losses. Rough cost-benefit analyses have been carried out in order to compare the sustainability of alternative seismic rehabilitation techniques, thus providing a rational base and objective criteria that can be used in the design and/or preliminary screening phase by insurance companies, to reduce the seismic risk and the impact of earthquakes on a community.