Lateral Load Capacity of Unreinforced Block Masonry Walls: Mortar Strength and Block Type Considerations

This paper presents the results of experimental testing of unreinforced masonry (URM) wall panels that were subjected to diagonal compression and shear-compression loads. These panels were made of four types of concrete blocks by combining them with two mortar grades including 1∶3 (cement:sand by weight) (designated as M3) and 1∶6 (designated as M6). The diagonal compression test panels were made of M3 mortar grade for a comparison of behavior with shear-compression wall panels. Both of these types of panels exhibited (generally) a diagonal tension failure. Conversely, the shear-compression test panels made of M6 mortar grade failed by a combination of joint sliding, diagonal tension cracking, and toe crushing. The tensile strength of the panels tested in shear compression was higher compared to the similar panels tested in diagonal compression. On the other hand, the tensile strength and stiffness of a panel lowered with a decrease in mortar strength. The displacement capacities and ductility of the tested panels ranged from 0.62% to 2.87% and 0.12 to 0.57, respectively. This signifies satisfactory deformation capacity but limited ductility characteristics of these URM walls. The analytical method based on direct shear strength assessment provided realistic estimates of the wall lateral load capacity. An analytical capacity curve has been proposed for the structural assessment of URM in-plane walls.