MODELLING SFRC WITH A STRESS-STRAIN APPROACH

Steel Fibre Reinforced Concrete (SFRC) is a tension softening material. This means that once a single crack has been formed the residual post-cracking tensile strength in that section is lower than the initial tensile strength. When increasing the deformation, the crack will open and the post-cracking tensile stress, carried by the crack-bridging fibres, will decrease. For this type of material a stress-crack width relation can easily describe the basic constitutive material behaviour. However, since most design engineers are more confident with a stress-strain relation, it is investigated whether a stress-strain relation is able to accurately predict the structural behaviour of SFRC. In the paper a proposal is made to derive a stress-strain relation from the results of a RILEM 3-point bending test. The proposal is based on the assumption that the influence of the crack stretches in both directions over a length equal to the height of the tensile zone. The length of this influence zone is called characteristic length. Dividing the crack width by the characteristic length results in a “virtual” tensile strain. The newly proposed stress-strain relation is used to predict the loaddeflection behaviour of 28 full-scale beams. The results indicate a good prediction of the structural behaviour.

• INTRODUCTION

• DERIVING A STRESS-STRAIN RELATION

• EXPERIMENTAL PROGRAM ON FULL-SCALE BEAMS

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES