Strengthening of reinforced concrete beams using ultra high performance fibre reinforced concrete (UHPFRC)

• Experimental investigation was conducted to determine mechanical properties and shrinkage of UHPFRC.
• Numerical model was developed for the simulation of UHPFRC.
• The efficiency of UHPFRC layers and jackets for the strengthening of existing beams was assessed.
• Superior performance was observed in terms of stiffness, yield and maximum strength, when three side UHPFRC jacket was used.

In this study the efficiency of the use of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) for the strengthening of existing Reinforced Concrete (RC) beams has been investigated. Experimental work has been conducted to determine UHPFRC material properties. Dog-bone shaped specimens have been tested under direct tensile loading, and standard cubes have been tested in compression. These results have been used for the development of a numerical model using Finite Element Method. The reliability of the numerical model has been validated using further experimental results of UHPFRC layers tested under flexural loading. Further numerical study has been conducted on full-scale beams strengthened with UHPFRC layers and jackets, and these results were compared to respective results of beams strengthened with conventional RC layers and with combination of UHPFRC and steel reinforcing bars. Superior performance was observed for strengthened beams with UHPFRC three side jackets, and the efficiency of this technique was highlighted by comparisons with other strengthening techniques.