Although the issue of the out-of-plane response of unreinforced masonry structures under earthquake excitation is well known and consensual between the research community, this is simultaneously one of the more complex and most neglected areas on the seismic assessment of existing buildings. Nonetheless, its characterisation should be found on the solid knowledge of the phenomenon and on the complete understanding of methodologies currently used to describe it. Based on this assumption, this paper presents a general framework on the issue of the out-ofplane performance of unreinforced masonry structures starting off with a brief introduction to the topic, followed by a compact state of art in which the principal methodologies proposed to assess
Downloaded by [Selcuk Universitesi] at 05A c c e p t e d M a n u s c r i p t 3 the out-of-plane behaviour of unreinforced masonry structures are presented. Different analytical approaches are presented, namely force and displacement-based, complemented with the presentation of existing numerical tools for the purpose presented above. Moreover, the most relevant experimental campaigns carried out in order to reproduce the phenomenon are reviewed and briefly discussed.