Bounding Surface Model For Concrete In Triaxial Compression

With the widespread availability of high-strength concrete, great achievement has been made on research of constitutive model for concrete. All kinds of constitutive models for concrete appear. But they all have their merits and demerits. The mechanical behavior of concrete is very complex, such as nonlinear multi-axial stress-strain, shear compaction-dilatation behavior, strain-softening and stiffness degradation under cyclic loadings. Especially the bounding surface model is being paid great attention to, because of its superiority on reliable simulation and few parameters.A bounding surface model for concrete in triaxial monotonic and cyclic compressions is developed based on the theory of bounding surface and continuum damage mechanics. It adopts a damage concept to characterize progressive stiffness degradation and to capture nonlinear behavior. A realistic modeling of the damage accumulation under complex stress paths can be achieved by defining K. From tests, plastic deformation will happen under small compression; Among some proportional loading, dilation will happen while beyond the proportional dilation will not happen. There is a connection between bounding surface and damage parameter. When damage parameter achieved a value, bounding surface begin to contract to model strain softening of concreteThe model can be applied in finite element program of monotonic and cyclic compression of concrete easily because of few input parameters. Comparison of the stress strain results indicates good agreement between the theoretical model and the experimental data.