Numerical modelling of the concrete/rebar bond

The simulation of the behaviour of the rebar–concrete bond is of primary importance for an accurate description of cracking processes in reinforced concrete structures and an improved prediction of their durability. In this paper, the methodology used to identify the mechanical behaviour of a rebar-concrete bond in the case of a particular steel reinforcement is first mentioned. The methodology consists in simulating the probabilistic mechanical behaviour of RC tie-beams (170 × 10 × 10 cm), subjected to tension, using a probabilistic approach for the mechanical behaviour of the concrete and a deterministic model for the concrete/rebar bond. The tie-beams are reinforced by a flat steel rebar with a rectangular cross section (25 × 3.5 mm).This approach at macro-scale level is compared to another one at micro-scale level in which notches/indentations of the flat steel rebar are explicitly taken into account in the simulation, the bond behaviour being considered through the local concrete cracking around the rebar.The following conclusions can be made from this study:
• The modelling of the concrete/rebar bond by an interface element having damage behaviour is relevant if the modelling of concrete cracking is physically and quantitatively relevant.
• The concrete/rebar bond behaviour can mainly be considered as the consequence of concrete micro-cracking around the ribbed rebar (it means due to the presence of notches/indentations).
• This micro-cracking concerns a zone with a thickness similar to the rebar one.