Fundamental Investigations on the Performance of Micro Steel Fibres in Ultra-High-Performance Concrete under Monotonic and Cyclic Tensile Loading

Ultra-high-performance fibre-reinforced concrete (UHPFRC) can preferably be used for lean and thin-walled structures due to its very high compressive strength. Based on the adverse relation between the increased load bearing capacities and the condensed dead weight of UHPFRC-structures, the impact of live loads in the design gets bigger and, in case of traffic loads, the effects of a cyclic loading have to be considered in more detail. In this context, this study investigated the material behaviour of UHPFRC, especially the tensile fatigue behaviour of high-strength micro steel fibres and the bond behaviour between those fibres and plain UHPC. The test programme included once tensile tests of high-strength micro steel fibres under monotonic and cyclic loading. Based on the test results, an S/N-curve was set up with the characteristic values. Furthermore, the test programme included pullout tests of fibre groups with different embedded lengths and orientations under monotonic and cyclic loading. It was observed that some fibres rupture under certain test configurations like the angle of orientation and the load amplitude.