A Numerical Investigation on the In-Plane Behavior of Perforated Unreinforced Masonry Walls

Considering architectural constraints, the existence of openings in unreinforced masonry (URM) walls is inevitable. Moreover, the observations of damaged URM buildings after previous earthquakes and the results of experimental studies on the seismic performance of masonry shear walls confirm that the in-plane behavior of perforated walls depends on the coupling of piers and spandrels. Accordingly, some improvements have been made in recent editions of international seismic retrofitting codes. This study is concerned with the in-plane behavior of perforated URM walls through a finite element (FE) study. For this purpose, 3D micromodeling is utilized for the simulation of the masonry walls in the FE software ABAQUS. At first, the FE model is verified using the results of an experimental study on large-scale perforated walls under simultaneous gravity and lateral in-plane loads. The numerical and experimental results show a good agreement with each other which confirms the reliability of the model for the simulation of URM walls. Subsequently, a parametric study is conducted by means of the validated FE model. The pier width and spandrel depth of the walls as well as the intensity of the gravity load on the piers are considered as the influential variables in the numerical investigation. Finally, the results of the numerical study are presented in terms of load-displacement curves, ultimate mode of failure, and the proportions of the internal shear force induced in piers at different story drift levels. According to the results of the current study, the geometrical properties of the walls and the gravity load have a substantial effect on the in-plane strength of the walls. Additionally, the role of spandrels in the global seismic performance of URM walls and piers is not negligible and should be considered in the seismic vulnerability assessment of existing buildings.