Predicting the Shear Behavior of Reinforced Concrete Beams Using Non-linear Fracture Mechanics

This paper deals with the challenging problem of predicting the load carrying capacity of reinforced concrete shear-critical beams. To simulate the cracking behavior of concrete, the discrete crack approach based upon non-linear fracture mechanics is used. An algorithm with two pathways of implementation has been proposed so as to implement fictitious crack model to analyze reinforced concrete beams using finite-element method. The merit of the proposed algorithm is its capability to recognize and to incorporate them in the analysis procedure. The proposed method is capable of predicting simultaneous multiple shear cracks, load-deformation behavior, and ultimate shear capacity of reinforced concrete beam. The obtained results show a good compliance with the available experimental benchmark studies on reinforced concrete beams failed in shear. As one of the important aspects of shear capacity is the size effect issue, some large-scaled test beams have been numerically simulated using the proposed algorithm and the results have been compared with that of ACI 318-11 building code as well as the well-known modified compression field theory (MCFT). The comparison corroborated the robustness of the proposed algorithm in detecting the well-known shear-scaling phenomenon. In the same time, the comparison emphasized on the weakness of the current codes of practice to overestimate the shear capacity of large-scaled beams owing to not taking the size effect into account.