Abstract
Strut-and-tie and stress field models have become widely accepted as reliable rational tools for design-ing concrete structures, particularly disturbed concrete regions (D-regions) where the beam theory assumptions are not valid. Typical examples include deep beams, corbels, dapped-end connections, and regions around openings. Early and recent developments in strut-and-tie and stress field models have allowed D-regions to be designed at ULS using a robust approach at various levels of approximation: from simple calculations to detailed numerical analysis. However, there is little guidance on their ap-plicability under SLS conditions. This lack of knowledge is particularly important for the crack behavior of D-regions, as they often develop localized cracking near re-entrant corners and openings. These localized cracks reach large openings at low loads and cannot be modelled based on the available meth-ods for beam regions. This paper will therefore discuss a framework for evaluating in a consistent manner localized and distributed cracks in D-regions. The approach consists of two steps: evaluation of the reinforcement strains in cracks (using e.g. strut-and-tie and stress field models) and establishing a link between the strain and the width of the crack. Depending on the purpose of the calculation, each step can be conducted using various levels of approximation.
