Description
Bridges are designed for a service life of up to 100 years. Hence, and as older design codes are partly obsolete today, a significant number of structures still in use lack the required levels of resistance and exhibit heavy deterioration. With the increasing focus of the construction industry towards sustainability and circularity, there is a trend to develop innovative and efficient strengthening methods that enable the repair of under-designed or damaged structural components rather than rebuilding new structures. To this end, this paper presents a research project aiming at developing a new method for flexural strengthening of bridge decks, which consists in applying a top layer of Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) prestressed with iron-based shape memory alloy (Fe-SMA) bars over the existing Reinforced Concrete (RC) structure.
To analyse this novel technology, a case study is developed. The performance of the new system is compared to the strengthening using B500B steel reinforcing bars embedded in UHPFRC and the main advantages of the new method are highlighted. Furthermore, a detailed characterisation of the bond behaviour of Fe-SMA bars embedded in UHPFRC is carried out through component-level bond tests. Design parameters such as the temperature of activation of Fe-SMA, the concrete cover and the bar material are studied. The bond-slip relationships show very high bond strengths, even after a slight deterioration of the bond properties resulting from the heating.
