Tension Failure Criteria for Plain Concrete Masonry

Failure criteria for the tensile strength of ungrouted and grouted unreinforced concrete masonry are developed. These criteria account for the strength variation due to the anisotropic nature of masonry as a composite material. The tensile strengths normal and parallel to the bed joints are described in terms of the strength and geometric characteristics of the block, mortar, and grout. The diagonal tensile strength is described as a function of the strengths normal and parallel to the bed joints. Tension failure and combined sheartension failure are the two possible failure modes that were considered in the development of the failure criteria for tension parallel to the bed joint and for diagonal cracking. The predicted ultimate strengths using the proposed expressions are compared with experimental results for splitting tests of ungrouted and grouted masonry disks. Good agreement is shown, and it is concluded that the proposed criteria can be used to evaluate the influence of the stress orientation and the effect of varying the different strength and geometric properties of the components on the tensile strength of concrete block masonry.