Shear in Discontinuity Regions

This is the authors' abstract. We don't add key points for this paper.

he strut-and-tie method was introduced into "Building Code Requirements for Structural Concrete" (ACI 318) in 2002, 1 although its origins date to the end of the nineteenth century. 1 The ACI 318-02 version of the strut-andtie method is largely based on a 1987 report by Schlaich et al. 2 that describes procedures for designing structural elements using a system of struts and ties connected at nodes.The method is primarily intended for regions of the structure where the stress flow is influenced by concentrated loads, corners, openings, or other discontinuities.Such regions are referred to as discontinuity regions or D-regions.Strain distribution in D-regions is highly nonlinear, and the assumption of plane sections remaining plane does not apply.The strut-and-tie method is especially useful in D-regions because it allows for designing and detailing of the concrete section and reinforcement in accordance with a clearly visualized force field that is in static equilibrium, rather than relying on past practices or restrictive empirical guidelines.However, as will be explained in this article, there are several concerns and inconsistencies in the current Code (ACI 318-14 3 ) related to shear strength in D-regions:• Except for members qualifying as deep beams, minimum distributed reinforcement is not required in a D-region designed by the strut-and-tie method;