Behaviour and Strength Prediction of reinforced Concrete Structures with Discontinuity Regions

Abstract

This report presents an analytical study on reinforced concrete members with disturbed stress and strain states which are mainly caused by geometrical irregularities and loading conditions. Finite element methods are used as a tool to investigate the reliability of a non linear elastic material model which represents a direct description of the behaviour of reinforced concrete on macro level for short time loading. A three dimensional variation of the modified compression field theory with a rotating smeared crack approach forms the basis for the work.

Some modifications both on the compression and tensile side are suggested. The modifications are believed to improve the representation of the behaviour of reinforced concrete.

The model is verified on several single element tests. Extensive comparisons with findings from well documented experiments are made. Emphasis is put on the prefailure behaviour of the concrete, ie the deformation, crack growth, strain development in both reinforcement and concrete and the prediction of the failure load and failure mode. The model is proven to simulate the behaviour of the experiments with rather coarse element meshes and without extensive parameter optimization.

The reliability of simple analytical predictions of the failure load is also investigated. Such predictions are used to verify the finite element results in cases where the ultimate capacity is not known through experiments.