Performance of a novel ultra-durable hollow UHPC slab reinforced with prestressed Fe-SMA bars

This paper presents a novel type of hollow ultra-high-performance concrete (UHPC) slab reinforced with iron-based shape memory alloy (Fe-SMA) to enhance its performance, while a hollow UHPC slab strengthened with conventional steel is employed as reference. The shape memory effect of Fe-SMA is activated through the autoclave curing with temperature of 200°C. The flexural performance and anti-cracking ability of the hollow UHPC slab are investigated through four-point bending tests and 3D digital image correlation (DIC) measurements. The findings demonstrate the utilization of Fe-SMA modifies the failure mode of hollow UHPC slab by decelerating crack propagation compared to those reinforced with conventional steel. Hollow UHPC slab reinforced with Fe-SMA exhibit improved crack resistance (by about 40%), enhanced peak load (by about 65%) and improved deformability (by 20%) in comparison to the reference group. Fe-SMA and UHPC show higher compatibility from the aspect of ductility by comparing it with ordinary concrete. Finally, the calculation methods of flexural capacity are proposed, which offers valuable guidance for practical engineering. The incorporation of Fe-SMA presents promising prospects for enhancing both flexural performance and anti-cracking ability of hollow UHPC slab.