Out-of-plane behaviour of unreinforced masonry infill walls: Review of the experimental studies and analysis of the influencing parameters

Over the last 50 years, research has mainly focused on characterizing the In-Plane behaviour of unreinforced masonry infill walls. Recently, the focus of research has been addressed to understanding Out-of-Plane behaviour, also from the experimental point of view. However, in the experimental campaigns, there is high variability in the geometrical and mechanical properties of URM infill walls and also in the application of Out-of-Plane loads. Therefore, it is important to outline and critically evaluate the major findings obtained by experimental studies and identify research gaps to better understand the differences and the affinity of apparently equivalent tests. In this paper, the extensive literature regarding the Out-of-Plane tests on infill walls has been reviewed with a detailed comparison of the experimental results based on different influencing parameters (slenderness ratio, aspect ratio, boundary conditions, openings, vertical load. In-Plane damage, strength of masonry and plaster, frame stiffness). Based on the study, the main areas that demand further experimental campaigns have been identified and recommended.