Investigation of Shear Behavior of Concrete Block Masonry

Abstract

This paper presents the results of experimental testing that was conducted to determine the shear strength parameters of masonry specimens. These specimens were made of four types of concrete masonry units (CMUs) which were combined with two mortar grades including 1∶2 (cement:sand by weight) (designated as M2) and 1∶3 (designated as M3). Diagonal compression wall panels and masonry triplets were included in the testing program. Whereas the masonry triplets failed in shear bond, a diagonal tension failure was found for most of the wall panels tested in diagonal compression. The maximum shear strength (τmax) and shear modulus (Gm) of both types of specimens were influenced by the mortar strength (fm) and were (nearly) insensitive to the CMU strength. τmax of diagonal compression wall panels was considerably high based on the assumption of uniform distribution of shear stress by the relevant testing standard in the United States. On the other hand, it became comparable with the triplet τmax when determined by the European standard which considers nonuniform shear stress distribution for the masonry panel. The average τmax were 0.018fm and 0.019fm for the triplets and diagonal compression wall panels, respectively. Analytical methods have been proposed to determine τmax and Gm of masonry made of CMUs as a function of fm which avoids the determination of masonry compressive strength for this purpose.