Manufacturing and performance of a novel self‐centring damper with shape memory alloy ring springs for seismic resilience

Abstract

Summary This paper discusses the manufacturing process and mechanical performance of a novel self‐centring damper equipped with a group of kernel elements, namely, shape memory alloy (SMA) ring springs. The study commences with an experimental investigation on individual SMA ring spring specimens, enabling a fundamental understanding of their working principle and mechanical performance. Some technical issues related to manufacturing process, low‐temperature heat treatment (annealing), quenching, and cyclic training are also discussed. Subsequently, the fabrication steps and working mechanism of the dampers incorporating the SMA ring springs are elaborated, and a further experimental study on a large‐scale prototype damper specimen is carried out. The test results show that the damper specimen exhibits satisfactory mechanical behaviour with a stable flag‐shaped load–displacement hysteretic response. A high initial stiffness and an adequate level of “yield” resistance are exhibited due to a relatively high preload applied to the SMA ring spring group. Excellent self‐centring capability with no residual displacement is observed, and satisfactory energy dissipation with an equivalent viscous damping ratio of up to 18.5% is shown. No failure to any component of the damper is observed by the end of the test. The proposed damper is expected to resist strong earthquakes and offer self‐centring driving action effectively for engineering structures without the need for repair.

Seismic robustness of self‐centering braced frames suffering tendon failure

“…The available interstory drift observed from most of these investigations generally ranges between 2% and 2.5% before failure of the PT tendons, and this level of ductility supply could be insufficient for steel frames under strong earthquakes. Other researchers have employed shape memory alloys (SMAs) to provide significantly increased deformation capacity and extra energy dissipation thanks to the superelastic effect, 24–33 although the temperature dependency and cost issues need to be carefully addressed. A recent study conducted by Chen et al 34 found that anchor slippage was the main failure mode for SCBs with SMA tendons.…”

Design and experimental verification of disc spring devices in self‐centering reinforced concrete shear walls

“…As the first seismic defense line, such RC shear walls are usually severely damaged, and excessive residual deformations often occur in these structural walls after an earthquake, thus resulting in enormous costs for postevent repair and additional downtime losses. Therefore, in recent years, many efforts have been made to develop self‐centering (SC) systems that can effectively reduce the residual deformation and control the damage of structures 1–6 . Unbonded posttension (PT) tendons were first used in self‐centering wall systems to provide restoring forces to return the structure to its original position after an earthquake; such wall include the application of unbonded posttensioned precast concrete walls proposed by Perez et al 7 precast concrete walls with end columns proposed by Sritharan et al 8 and self‐centering shear walls with horizontal bottom slits proposed by Lu et al 9 Wall systems using unbonded PT tendons have been demonstrated to exhibit good self‐centering capabilities.…”

Experimental study of new axial recentering dampers equipped with shape memory alloy plates

“…One of these retrofitting methods is using shape memory alloys (SMAs) in a structure for the purpose of reducing permanent deformation as well as increasing energy dissipation. The SMA materials have a flag‐shaped behavior with two unique properties called superelastic and shape memory effect 12–18 . These properties correspond to phase transformation from martensite to austenite and vice versa.…”

“…These properties correspond to phase transformation from martensite to austenite and vice versa. There are several studies regarding SMA dampers and their performance in the frame structures 17,19–31 …”