Shear Capacity of RC Membrane Elements Subjected to Pure In-Plane Shear Stresses

This study evaluates the shear capacity of reinforced concrete (RC) membrane elements subjected to pure inplane shear stresses at different levels of loading. These elements are shown to fail in four different modes. A model is proposed for the shear capacity of these membrane elements that can be computed by direct simple expressions without the need to any iterative process as is usually the case in existing models. Failure in these membrane elements is generally preceded by the formation of two or more major critical cracks assumed herein to propagate in a direction normal to the principal tensile stresses in the concrete. At each stage of loading, the major critical cracks are shown to open at an optimum angle that corresponds to the least shearing resistance to external loading. Major cracks as well as ultimate shear capacity of RC membrane elements are shown to occur when the contribution of the x-reinforcement to resist shear stresses is equal to that of the y-reinforcement. Experimental results of tests on RC membrane elements subjected to pure inplane shear stresses obtained from literature are used to validate and compare the proposed model with existing models. Examples are provided for the computations of shear capacity by the proposed model for the different modes of failure.