Effect of Loading Rate and Initial Strain on Seismic Performance of an Innovative Self-Centering SMA Brace

Abstract

In order to improve the energy dissipation capacity and to reduce the residual deformation of civil structures simultaneously, this paper puts forwards an innovative self-centering shape memory alloy (SMA) brace that is based on the design concepts of SMA’s superelasticity and low friction slip. Seven self-centering SMA brace specimens were tested under cyclic loading, and the hysteresis curves, bond curves, secant stiffness, energy dissipation coefficient, equivalent damping coefficient, and the self-centering capacity ratio of these specimens were investigated, allowing us to provide an evaluation of the effects of the loading rate and initial strain on the seismic performance. The test results show that the self-centering SMA braces have an excellent energy dissipation capacity, bearing capacity, and self-centering capacity, while the steel plates remain elastic, and the SMA in the specimens that are always under tension are able to return to the initial state. The hysteresis curves of all of the specimens are idealized as a flag shape with low residual deformation, and the self-centering capacity ratio reached 89.38%. In addition, both the loading rate and the initial strain were shown to have a great influence on the seismic performance of the self-centering SMA brace. The improved numerical models combined with the Graesser model and Bouc–Wen model in MATLAB were used to simulate the seismic performance of the proposed braces with different loading rates and initial strains, and the numerical results are consistent with the test results under the same conditions, meaning that they can accurately predict the seismic performance of the self-centering SMA brace proposed here.

Mechanical Behavior of Shape Memory Alloy Fibers Embedded in Engineered Cementitious Composite Matrix under Cyclic Pullout Loads

“…Therefore, it has been widely used in self-centering seismic structures in recent years. Jia et al [15] studied the seismic performance of SMA brace specimens through a cyclic loading test. The test results show that the SMA brace has good energy dissipation capacity, bearing capacity and self-centering ability.…”

Shape Memory Alloys for Civil Engineering

“…The proposed approach was validated by experiments. Papers [ 2 , 3 , 4 , 5 ] focus on the applications of SMAs in braces and connections in residential buildings/industrial structures. Zhang et al [ 2 ] present a novel type of hybrid self-centering braces incorporating tension-only superelastic NiTi shape memory alloy (SMA) cables and integrated viscoelastic dampers (VEDs).…”

“…Their new design demonstrates an enhanced energy dissipation ability and self-centering tendency compared with existing SMA-based self-centering solutions, where its improved behavior mainly stems from the participation of the VEDs. Jia et al [ 3 ] have developed an innovative self-centering SMA brace based on low friction slip. This study comprehensively evaluates the effects of the loading rate and initial strain on the seismic performance of the SMA braces.…”

“…The above nine papers [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ] have focussed on NiTi SMAs. Iron-based SMAs (Fe-SMAs), also known as Fe–Mn–Si alloys, are another member of the family of smart metals for civil engineering.…”