Studies on the existing in-plane shear equations of partially grouted reinforced masonry

This paper provides critical analyses of the presence of the reinforced grout cores within the masonry walls with particular reference to the existing in-plane shear design expressions in several national standards; these expressions comprise terms which define the shear strength of masonry, the vertical load and the area of reinforcement. These expressions treat the wall height to length ratio (termed as wall aspect ratio) as a prime factor in their respective masonry strength terms. The consideration of the wall aspect ratio in these design expressions implies existence of a compression strut along the wall diagonal, although such a phenomenon is not established in the literature. In this paper, through an extensive analyses of partially grouted reinforced masonry shear walls using a validated nonlinear finite element model, it is shown that the aspect ratio of the unreinforced masonry panels inscribed within the vertical and the horizontal reinforced grouted cores has profound effect on the in-plane shear capacity of the walls. It is also shown that the horizontal and the vertical reinforcements do never yield and hence their inclusion in the in-plane shear capacity expressions is not justified. A recently reported expression by the authors is also reviewed and compared with the other international design expressions.