Strutture intelaiate e tamponate in c.a.: sperimentazione e sviluppi nella modellazione analitica e numerica

The presence of masonry infills in RC structures may have a fundamental role in response under seismic excitation, especially in the case of structures designed for gravity loads only and without seismic details. Studies of many authors show important modifications of response in terms of strength, stiffness, ductility and safety evaluation. The recent large development of nonlinear seismic, static and dynamical methods requires a relevant effort in modelling with a reliable, and at the same time easy for practical using, constitutive laws for infill panels. In this context the present study provide an experimental investigation on single story, single bay, half scale frames, fully infilled with different kinds of masonry and subjected to lateral cyclical loads showing the relevant role of infills in structural response depending also from masonry mechanical properties. A suitable way for modelling this phenomena in FEM codes is the choice of a multi linear plastic link element with a Pivot hysteretic law appropriately calibrated on experimental results. In this paper, experimental campaign results for before mentioned infilled frames are presented in comparison with numerical response of the proposed modelling with a pivot model law. Calibrating strategy and consequent suggested values for the parameters of the pivot model are also provided.