ABSTRACT

The modelling and simulation of fatigue behaviour of fibre-reinforced concrete is challenging due to the different length scales of fibres, grains, pores, cracks and the structural component itself. To calculate the necessary number of load cycles by using complete models or by using standard multi-scale models leads to a huge computational effort. The computational costs easily exceed technical limits. The proposed solution via a fibre super-element overlay mesh separates the mesh of the concrete matrix from the one of the fibres. In this manner, strong mesh refinements towards the fibres can be avoided. Moreover, both meshes can be connected by linear constraints, implemented via the known elimination method. Then, the computational effort is mainly determined by the applied matrix mesh. All degrees of freedom of the fibre super-elements do not enter the final system of equations, which needs to be solved. The method requires one-dimensional fibre elements with variable numbers of nodes. The implemented super-element models the effective behaviour along the whole fibre channel by an embedded Finite Element approach. It covers the bonded fibre behaviour as well as the debonding process and fibre pull-out behaviour. The model parameters are obtained from fibre pull-out tests.