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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. DOI: 10.1061/(ASCE)0733-9445(2002)128:12(1519) CE Database keywords: Compression; Discontinuities; Concrete, reinforced; Shear; Strength.

A softened strut-and-tie model for determining the shear strength of squat walls is proposed in this paper. The proposed model originates from the strut-and-tie concept and satisfies equilibrium, compatibility, and constitutive laws of cracked reinforced concrete. The shear capacities of 62 squat walls were calculated and compared with the available experimental results, and reasonable agreement was obtained. Based on the collected experimental data in this paper, the proposed physical model was used to study the effects of boundary elements, cyclic loading, and vertical loads on the wall shear strength. The softened strut-and-tie model can be further developed to improve the current shear wall design procedures by incorporating the actual shear resisting mechanisms in predicting shear strength of walls.