Output-only modal testing and model validation of unreinforced masonry infill walls in reinforced concrete frames

Unreinforced masonry (URM) infill walls in reinforced concrete (r.c.) buildings are prone to seismic damage due to combined in-plane (IP) and out-of-plane (OOP) loadings. In particular, damage due to IP displacement demands promotes OOP collapse of URM infills (IP-OOP interaction). Thus, an experimental campaign based on static, cyclic and dynamic tests has been initiated to assess the influence of IP damage on the OOP response of masonry infills in r.c. frames. The present paper investigates the OOP dynamic response of 2D frames with URM infills in healthy state, when no cracking is present in the masonry panel as a result of IP static or cyclic tests. A finite element model of the frames is developed and validated against the results of output-only modal tests. Finally, sensitivity analyses are carried out to assess the relative influence of boundary r.c. elements on the OOP dynamic response of the panel.