Superelastic Nickel–Titanium (NiTi)-Based Smart Alloys for Enhancing the Performance of Concrete Structures

Abstract

Recent advances in materials science have led to the development of smart materials that can continuously adapt to different loading conditions and changing environment to meet the growing demand for smart structural systems. The unique characteristics of superelastic NiTi shape memory alloys (SMAs) have attracted the attention of structural engineers worldwide. SMAs are metallic materials that can retrieve their original shape upon exposure to various temperatures or loading/unloading conditions with minimal residual deformation. SMAs have found increasing applications in the building industry because of their high strength, high actuation and damping capacities, good durability, and superior fatigue resistance. Despite the research conducted on the structural applications of SMAs during the previous decades, the existing literature lacks reviews on their recent uses in building industry such as prestressing concrete beams, seismic strengthening of footing–column connections, and fiber-reinforced concrete. Furthermore, scarce research exists on their performance under corrosive environments, elevated temperatures, and intensive fires. Moreover, the high manufacturing cost of SMA and the lack of knowledge transfer from research to practice are the main obstacles behind their limited use in concrete structures. This paper sheds light on the latest progress made in the applications of SMA in reinforced concrete structures during the last two decades. In addition, the paper concludes with the recommendations and future opportunities associated with expanding the use of SMA in civil infrastructures.

Numerical Investigation on the Performance of Exterior Beam–Column Joints Reinforced with Shape Memory Alloys

“…This level is important for mitigating the residual displacement of the joint without sacrificing the energy dissipation of the structure. Second, the range of the elastic modulus for SMA bars was selected based on the test results reported by some researchers [8,19,33]. This range had an important effect on the stiffness of the RC joint itself.…”

“…Recently, with the increased awareness of the importance of residual displacements, several novel systems have been investigated to mitigate their effects and improve displacement recovery. A promising new way of resolving this problem is to use smart materials such as SMA in reinforced concrete joints [6][7][8][9][10][11][12][13][14][15][16].…”

Development and Performance Evaluation of a Mechanical Connection for Steel and Shape Memory Alloy Bars

“…In addition, research has also pursued stress recovery and crack closure capabilities of cold-drawn and rolled wires [12,13]. Subsequent research has been conducted using SMA wires to prestress structural elements [14,15], and research continues to apply SMAs to structural members using various methods [16][17][18][19][20].…”