Description
The utilization of iron-based shape memory alloys (Fe-SMA) can significantly enhance the mechanical properties and durability of civil engineering structures as prestressing tendons. The martensitic transformation-induced self-prestressing force, resulting from temperature changes, offers a more convenient approach to generate prestress compared to traditional method, which is suitable for applying prestress in thin-walled curved components. The present study involves the design of a novel type of ultra-high-performance concrete (UHPC) shell structure reinforced with Fe-SMA to enhance its load carrying capacity, while an UHPC shell strengthened with conventional steel is employed as reference. The shape memory effect of Fe-SMA is activated through the utilization of high-temperature steaming curing. The load carrying capacity and anti-cracking ability of the UHPC shell are investigated through four-point bending tests and 3D digital image correlation (DIC) measurements. The findings demonstrate that UHPC shells reinforced with Fe-SMA exhibit enhanced load carrying capacity, superior energy absorption, and improved deformability in comparison to the reference group. Increasing the steaming curing temperature within a certain range can increase the recovery stress, resulting in improvement in the cracking load. However, this temperature effect diminishes with further increases in the curing temperature. Importantly, the utilization of Fe-SMA also modifies the failure mode of UHPC shells by decelerating crack propagation compared to those reinforced with conventional steel. The incorporation of Fe-SMA presents promising prospects for enhancing both load-bearing capacity and resistance to cracking in UHPC shells.
