Finite element modelling of ultra high performance fibre reinforced concrete beams exposed to fire.

A number of research concerns have arisen in the concrete research community on the fire resistance of Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) beams, despite their improved mechanical properties at ambient temperature. The traditional experimental approach to performance-based fire resistance estimation comes with a lot of economic and physical constraints. The recent improvements in both computational power and algorithms suggest that a numerical approach to performance-based fire resistance estimation has the capability to solve some of these challenges. By building on the principle of the finite element method, in this study, finite element models of UHPFRC beams exposed to elevated temperatures in a fire were developed in a finite element software package ABAQUS. The developed finite element models were validated against experimental results reported in a previous experimental study on UHPFRC beams which were pre-loaded under load ratios of 0.2, 0.4 and 0.6 then subjected to 60-minutes ISO 834 fire in a furnace. The finite element model predicted the thermal and mechanical responses of UHPFRC beams which were in good agreement with results reported on the experimental beams. Subsequently, the finite element models were used in a parametric study to investigate the fire resistance of UHPFRC beams under nine different load ratios (0.1-0.9) and different heating regimes, that is, the ISO 834, and the hydrocarbon temperature-time curves and fire resistance ratings were estimated at 0, 30 or 60-minutes for the beams considered. It is hoped that the proposed finite element models be used directly for performance-based fire safety design of UHPFRC beams as a cost-effective numerical tool and be employed in parametric studies to develop simple prescriptive design rules.