Mesoscale finite element modelling of failure behaviour of steel-bar reinforced UHPFRC beams with randomly distributed fibres

This study develops a nonlinear finite element model for simulation of complicated failure behaviour of ultra high performance fibre reinforced concrete (UHPFRC) beams reinforced with steel bars and stirrups. In this model, the continuum damage plasticity model is used as the constitutive law for the UHPC matrix, and cohesive elements are used to simulate the softening bond-slip behaviour of the steel fibres/bars-UHPC matrix interfaces. Both the steel fibres and bars are modelled by elastic-plastic beam elements. As such, all the potential failure modes, including the matrix cracking and crushing, yielding and breakage of steel bars and fibres, and debonding of interfaces, can be simulated. A beam under four-point loading with various shear span versus beam depth ratios was simulated to validate the model. The results were compared well with experiments in terms of load-deflection curves and failure behaviour.