Strength Prediction for Discontinuity Regions by Softened Strut-and-Tie Model

Discontinuities caused by abrupt changes in cross-sectional dimensions or by concentrated loads result in discontinuity regions due to disturbance in the flow of internal forces. A simplified method, based on the softened strut-and-tie model, for determining the shear strength of discontinuity regions failing in diagonal compressions is proposed in this paper. Strength predictions of the resulting expressions correlate well with the 449 test results of deep beams, corbels, squat walls, and beam-column joints available from the literature. The proposed method incorporates the shear resisting mechanisms as postulated by the softened strut-and-tie model, and it is a function of the concrete strength, horizontal shear reinforcement, vertical shear reinforcement, and geometrical configuration of the discontinuity regions. A numerical example is included for illustration.