Computer-aided stress field analysis of discontinuity concrete regions

Strut-and-tie models and stress fields are widespread methods in engineering practice for the design of discontinuity regions. They are powerful tools that give the engineer control over the design, but they are not directly applicable for checking serviceability criteria and their use for the dimensioning of real-life structures often requires tedious iterative hand calculations. This paper presents a method for the design and assessment of discontinuity regions in concrete structures aiming at overcoming these limitations. The method consists of a FE-based computer-aided stress field analysis that implements uniaxial constitutive laws for reinforcement and concrete in compression. The tensile strength of concrete is neglected except for its stiffening effect on the reinforcement, and the effective compressive strength is automatically evaluated based on the principal tensile strain. The correlation with experimental results is excellent in terms of failure modes, ultimate loads as well as stiffness and crack widths.