Utilize Shape Memory Alloys for the Structural Intervention of Historical Structures

An emerging material with unique properties, ideal for various structural intervention techniques, is shape memory alloy (SMA). SMAs are special metallic alloys which, unlike classic metal alloys, have the ability to recover large deformations and return to a pre-determined shape through heating or unloading. SMAs possess several advantages over steel or fiber reinforced polymers (FRP). Their unique properties make them suitable in a variety of applications in structural intervention of historical constructions such as load-isolating, load-limiting and re-centering applications. Additionally, they have the ability to re-apply prestress forces that are lost due to straining of the material or slippage. Finally, SMA has a relatively high resistance to fire and corrosion. The first known application of using SMA bars for a structural intervention was in 2000 for a seismic retrofit for the bell tower of the Church of San Giorgio at Trignano, Italy after being damaged in a 4.8 Richter earthquake. The success of the intervention technique involving SMA bars was proven when the tower sustained another earthquake with the same epicenter and magnitude as the previous one, yet showed no signs of damage afterwards. This paper presents the state of the art review of utilizing SMA for the structural intervention of historical structures. It highlights the material’s unique characteristics and demonstrates its applicability in the field.