Propagation of a cohesive crack through adherent reinforcement layers

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This paper analyzes the propagation of a cohesive crack crossing one or several reinforcement layers by a simple model valid for any specimen or loading condition. In this instance the case of reinforced concrete beams loaded at three points is considered. In this approach steel bars do not constitute a physical barrier to the propagation of the crack, as concrete continuity is preserved by a computational strategy consisting of overlapping both materials in the same spatial position. The model uses cohesive elements to represent the crack and interface elements to simulate the decohesion and shear generated in the steel–concrete debonding process. The results given by this model are compared to experimental results on rectangular and T-shaped beams reinforced by bars arranged in one or several layers. The model closely follows the experimental trends when changing the parameters that control the type of fracture; such as the steel ratio, the bond strength, the position and arrangement of the bars, the size of the specimen and the shape of the beam cross-section. In spite of its simplicity, this model can be useful when studying local fracture and decohesion phenomena wherever they may take place within a reinforced or prestressed concrete structure.