Biaxial tension–compression strength behaviour of UHPFRC in-plane elements

Abstract

Ultra-high-performance fibre-reinforced concrete (UHPFRC) panel-shaped elements subjected to compression–tension loading are tested to investigate their in-plane structural behaviour under biaxial stress. Tension-stiffening and compression-softening ultra-high-performance concrete (UHPC) behaviours are analysed with and without fibre, based on the test results from 30 specimens subjected to various transverse tensile strains. The tension-stiffening bond factor of UHPC with fibre is found to be about twice that of UHPC without fibre. The compressive strength of a UHPC panel subjected to transverse tensile loading is decreased by 50 % without fibre and 30 % when the fibre is in the elastic range of the reinforcing bars. Sequential loading of biaxial stress onto UHPC is appropriate for determining the limited lower boundary for the reduction of compressive strength that characterises the transverse tensile effects of fibre reinforcement. In addition to the biaxial behaviour of the UHPC panel, the failure envelope of UHPC with and without fibre is suggested schematically by considering the existing references, and a failure envelope is proposed. The entire analytical investigation and proposed failure criteria will allow for the efficient optimisation of the geometries of UHPFRC structures.