Micro‐structure related modelling of ultra‐high‐performance fibre reinforced concrete (UHPFRC) subjected to cyclic tensile loading

Abstract

AbstractUltra‐high performance concrete with a compressive strength of more than 140 N/mm2 reacts very brittle without the addition of fibres. At designing economical and resource‐efficient building components as well as performance‐optimized materials, the supporting effects of the additional microfibres must be considered. Prospectively, cyclic loading and the fatigue behaviour of high performance materials and slim components will come to the fore. Therefore, the influence of cyclic deterioration on the load bearing capacity of the interface transition zone connecting microfibres and the surrounding concrete surface must be investigated. As part of the DFG Priority Programme 2020, the damage mechanisms and processes regarding the deterioration of UHPFRC subjected to cyclic tensile loading are explored in an Experimental‐Virtual Lab. Using the concepts of elasto‐plasticity and continuum damage mechanics, the material models for the components of the composite material UHPFRC are improved and enhanced to be combined on a mesoscale with the help of a non‐linear bond model. This bond model is discretized by interface elements with curved surfaces in 3D space and describes the interaction of fibres and concrete in the bond zone in terms of adhesion and friction effects. For validation and verification, single and multiple fibre pullout tests are simulated in 3D‐finite element analyses. These FE‐simulations and preliminary findings are supposed to provide the essential basis for future numerical degradation prediction.