Keywords: cracks, local, non-local, gradient, damage, constitutive models, regularization, localization, reinforced concrete.

A computational strategy for predicting cracks in reinforced concrete using local and gradient non-local formulations is described. A smeared damage approach is adopted for cracking and both local and non-local implementations are considered. The equations of isotropic damage model, based on that used of Oliver et al. [1], are summarised in the paper. The model has been used to simulate the concrete micro-cracking behaviour and discrete line elements used to represent the reinforcement.

A procedure for computing crack widths which can be incorporated in the finite element analyses of reinforced concrete structures is described. The primary issues examined are (i) the accuracy of the mean reinforcement strain computed in local and non-local models, when judged against code of practice equations and experimental data, and (ii) methods for calculating crack disposition and crack widths from the finite element strain fields.

The procedure is essentially a post-processing procedure in which mean reinforcement strains are extracted and used in combination with the Eurocode 2 formulae to predict crack widths.

An example is presented in the paper to illustrate the procedure for crack prediction. Experiment data are obtained from a test series on axially loaded reinforced prisms undertaken by Elfgren and Noghabai [2,3]. The results are promising and show that the method proposed does predict crack widths to an acceptable degree of accuracy.

1

J. Oliver, A.E. Huespe, M.D.G. Puilido, E. Chaves, "From continuum mechanics to fracture mechanics: the strong discontinuity approach", Engineering Fracture Mechanics, 69, 113-136, 2002. doi:10.1016/S0013-7944(01)00060-1

2

K. Noghabai, "Effect of Tension Softening on the Performance of Concrete Structures", Doctoral Thesis 1998:21, Luleå University of Technology, Division of Structural Engineering, 1998.

3

L. Elfgren, K. Noghabai, "Tension of reinforced concrete prisms. Bond properties of reinforcement bars embedded in concrete tie elements. Summary of a RILEM round-robin investigation arranged by TC 147-FMB Fracture mechanics to anchorage and bond", Materials and Structures, 35, 318-325, 2001. doi:10.1007/BF02483150

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