Cross-Section Influence on the Out-Of-Plane Behavior of Historic Masonry Walls

Out-of-plane (OOP) failure mechanism is a common collapse mode for unreinforced masonry walls in the lack of connections between structural members or when the wall cross-section is characterized by multiple leaves assembled without following the so-called rules of the art. Other factors influencing the OOP behavior are the transversal texture, presence of infill material, and mechanical properties of the constituent materials, i.e., unit and mortar joint mechanical properties. Furthermore, environmental conditions may negatively affect strength properties and cause aging and degradation. Currently, the main limitation of state-of-the-art tools stems from the practical difficulties of surveying the cross-section of historic masonry structures due to enormous costs and the limitations of performing destructive tests. Therefore, computational models should address the uncertainty in the material and geometrical properties to identify possible solutions for conserving historic masonry structures. This paper aims to determine the effect of cross-section geometrical morphology of unreinforced masonry walls. Throughout this study, a collection of masonry cross-sections is considered by different morphological properties, and their structural response is analyzed by performing pushover simulations with discrete element method (DEM). The effect of cross-section morphology on strength capacity and failure mechanism is critically discussed. Finally, a simple analytical equation is modified to take into account the imperfect connection of the masonry leaves.