Nonlinear Fracture Mechanics investigation on the ductility of reinforced concrete beams


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Title: Nonlinear Fracture Mechanics investigation on the ductility of reinforced concrete beams


Publication: IBRACON

Volume: 3

Issue: 2

Appears on pages(s): 137 148

Keywords: Nonlinear Fracture Mechanics, Reinforced concrete, Minimum reinforcement, Rotational capacity, Size effects, Codes provisions.

Date: 6/1/2010

In the present paper, a numerical algorithm based on the finite element method is proposed for the prediction of the mechanical response of reinforced concrete (RC) beams under bending loading. The main novelty of such an approach is the introduction of the Overlapping Crack Model, based on nonlinear fracture mechanics concepts, to describe concrete crushing. According to this model, the concrete damage in compression is represented by means of a fictitious interpenetration. The larger is the interpenetration, the lower are the transferred forces across the damaged zone. The well-known Cohesive Crack Model in tension and an elastic-perfectly plastic stress versus crack opening displacement relationship describing the steel reinforcement behavior are also integrated into the numerical algorithm. The application of the proposed Cohesive-Overlapping Crack Model to the assessment of the minimum reinforcement amount necessary to prevent unstable tensile crack propagation and to the evaluation of the rotational capacity of plastic hinges, permits to predict the size-scale effects evidenced by several experimental programs available in the literature. According to the obtained numerical results, new practical design formulae and diagrams are proposed for the improvement of the current code provisions which usually disregard the size effects.

Brazilian Institute of concrete, International Partner Access.

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