Structural Behaviour of UHPFRC Combined with Various Grades of Reinforcing Steel

Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) is a promising building material for applications where high compressive and tensile strengths, deformability and increased durability are required. Especially for the rehabilitation of existing structures, the addition of a thin cast-in-place UHPFRC layer onto a reinforced concrete member is very efficient. Structural resistance and deformability can be even more improved by incorporating reinforcing steel bars in the UHPFRC layer. To highlight the potential in terms of structural resistance and deformability and to reduce the variability of the mechanical properties of plain UHPFRC, UHPFRC with bar reinforcement is investigated in view of a reliable prediction of the structural response. This paper presents the results of an experimental program that serves to identify the fundamental structural response of reinforced UHPFRC, influenced by various types and ratios of reinforcement and their bond behaviour. These results validate an analytical approach considering the bond-slip law, the strain compatibility and the formation and opening of cracks. The understanding of the structural behaviour of reinforced UHPFRC establishes the basis to comprehend the behaviour of composite members combining reinforced UHPFRC and reinforced concrete.