Modeling of steel and concrete strains between primary cracks for the prediction of cover-controlled cracking in RC-beams

After cracking, the intact concrete between two consecutive primary cracks remains elastic and the maximum concrete stress is less than the tensile strength of concrete. However, under increasing loading, cover-controlled cracks occur at the steel–concrete interface causing a loss of bond and hence a loss of tension stiffness. The cover-controlled cracks are internal concrete cracks that initiate at steel rib location and are contained within the concrete cover. In this paper, steel and concrete strain distribution between two consecutive primary cracks are modeled based on a linear assumed distribution of the bond stress at the steel–concrete interface. The accurate calculation of the tensile concrete strain allows introducing new criteria for cover-control cracking initiation based on a peak value of steel stress calculated at crack location.

► Tension stiffening is modeled based on a linear assumed bond stress distribution between cracks.
► Non linear steel and concrete strain and neutral axis distributions between cracks are deduced.
► A criteria for cover-control cracking initiation versus loading is proposed.
► Cover-controlled cracking initiation results from an excessive axial tension strain in concrete.