Crack width control in two dimensional reinforced concrete elements

Physical models for two dimensional reinforced concrete elements design at ultimate limit state verification can be considered sufficiently well tested from both the scientific and normative viewpoint. It is still unsatisfactory, on the contrary, the study of serviceability behaviour of two dimensional elements designed at the ultimate limit state, especially as regards expected crack width control. This aspect of the issue is of particular interest also for D-regions in order to define the secondary reinforcement, that is not strictly necessary to ensure the equilibrium in the estimated ultimate condition. In this paper we aimed to find dimensioning criteria for secondary reinforcement in r.c. two dimensional elements, in order to ensure cracks of predetermined width in serviceability conditions. This aim can be achieved by a detail analysis of the structure behaviour that arises on the crack opening and following evolution, validating the obtained results by design procedures consolidated in international codes.