Finite element modelling of the biaxial behaviour of high-performance fibre-reinforced cement composites (HPFRCC) using Concrete Damaged Plasticity

High-performance fibre-reinforced cement or concrete composites (HPFRCC) are increasingly used in structural applications exposed not only to uniaxial but also complex stress states. Current finite element models for these materials have however been only validated for uniaxial stress states, and mostly restricted to cement composites with relatively limited strain hardening capacity in tension. To facilitate the numerical analysis and design of more complex structures, this paper adapts and validates the Concrete Damaged Plasticity (CDP) model for both uni- and biaxial stress states, and for cement composites with a large strain hardening capacity (ratio of failure stress to linear stress limit more than 8). The validation of the numerical model is done by performing laboratory biaxial tension-tension tests under various load cases. For the latter, an adapted cruciform specimen was designed. The strain distribution in the specimen as well as its evolution with increasing load correspond well. As the results show, the adapted CDP model can simulate the nonlinear strain hardening behaviour in tension - different from the linear behaviour in compression - of high-performance cement composites for both uniaxial as well as biaxial stress states. Moreover, failure can be simulated.