In-plane behavior of grouted concrete masonry under biaxial tension-compression

Thirty-six panels were tested to investigate the in-plane behavior of grouted concrete masonry under well-defined biaxial tension-compression loading conditions. In the panel tests, stresses are explicitly defined without the need to adopt any assumption of isotropic or elastic behavior. Thus, these tests are shown to be suited to the study of anisotropic characteristics, including cracked masonry and postyielding of reinforcement. The variables considered include the bed joint orientation, the principal stress ratio σ1/σ2, and the percentages of reinforcement normal and parallel to the bed joints. Modes of failure, strengths, and stress-strain relationships were found to depend on the bed joint orientation and the principal stress ratio. The degree of anisotropy varied, depending on the continuity of grout normal and parallel to the bed joints. Relating the effectiveness of shear reinforcement only to its total percentage was found to be incorrect. The tests showed that relatively large amounts of shear reinforcement can be beneficial to both shear strength and ductility, if attention is paid to the details and ratios of reinforcement.