Abstract

DENNEMAN, E; KEARSLEY, E P  and  VISSER, A T. Definition and application of a cohesive crack model allowing improved prediction of the flexural capacity of high-performance fibre-reinforced concrete pavement materials. J. S. Afr. Inst. Civ. Eng. [online]. 2012, vol.54, n.2, pp.101-111. ISSN 2309-8775.

In conventional concrete pavement design methods the design parameters are determined using linear elastic analysis. Concrete is subject to significant size effect and as a result linear elastic design concepts, such as the modulus of rupture determined for a beam, have limited reliability in the design of elements of different size and geometry. The objective of this paper is to demonstrate that, in contrast to the modulus of rupture, fracture mechanics material parameters can be used to accurately and precisely predict the flexural capacity of elements of a different size and geometry. The experimental framework includes two high-performance fibre-reinforced concrete mix designs, used to produce beams of different sizes tested in three-point bending configuration, as well as centrally loaded round panels. The fracture energy of the material is determined from the flexural beam tests. An adjusted tensile splitting test procedure is used to determine the tensile strength. The flexural tests on the beams and panels are simulated numerically using two finite element implementations of a cohesive crack approach. The numerical simulation yields satisfactory prediction of the flexural behaviour of the beam and disk specimens. It is concluded that using a fracture mechanics approach, the flexural behaviour of structural elements of different size and/or geometry can be reliably predicted.

Keywords : fracture mechanics; fibre-reinforced concrete; cohesive crack; flexural strength; size effect.

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