Analytical model to predict the out-of-plane response of masonry infill walls

The use of brick masonry infill walls is a common practice in reinforced concrete (RC) frames. These, classified as non-structural elements and often overlooked in design models, strongly influence the seismic behaviour of RC frames by increasing the overall structural stiffness. In addition, they can lead to significant structural irregularities and be the cause of brittle failure mechanisms, such as soft-floor mechanisms. This paper aims to present a recently developed analytical model for estimating the lateral out-of-plane (OOP) response of various masonry infill walls. This model implements vertical and horizontal arch mechanisms, including the deformability of the RC frame elements surrounding the panel (i.e., upper beam and columns), the possible presence of external strengthening solutions, and considering different failure mechanisms. The model is calibrated on the results of previous experimental campaigns for thin and thick infill walls, reinforced and unreinforced, also considering previous in-plane damage. Finally, a parametric analysis based on this model is presented, which is useful for discussing the role of the main vulnerability parameters of infills on their OOP capacity.