Enabling shape memory effect wires for acting like superelastic wires in terms of showing recentering capacity in mortar beams

Choi, Eunsoo; Ostadrahimi, Alireza; Lee, Yeonseong; Jeon, Jong‐Su; Kim, Ijung

doi:10.1016/j.conbuildmat.2021.126047

Cited by 15 publications

(7 citation statements)

References 44 publications

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“…Austenite starting (A S ) and finishing (A F ) temperatures can be extracted from differential scanning calorimeter (DSC, the device is DSC25 of TA instrument) test which are 48.05 • C and 110.16 • C, respectively (figure 1). Motivated by several benefits of wire crimping in terms of inducing prestressing effect [38][39][40][41], in this study a crimped wire is chopped to form several short fibers. Initially, the wire continuously is indented via a rolling device with a pair of 128 teeth gears to achieve a crimped wire with the height of 0.89 mm (figure 2).…”

Section: Geometry and Materials Parameters Of Ni-ti Fibersmentioning

confidence: 99%

“…After crack initiation, the SMA wires were heated by EH and induced recovery stress resulting in reducing crack opening points. Recently, several researchers have used electric current to heat the crimped SMA wire embedded in mortar beams [38,39]. In the test, the crimped SMA wire provided prestressing on mortar beams and showed great self-centering capacity during the cyclic bending tests, which was almost equal to that of the superelastic SMA wire.…”

Section: Introductionmentioning

confidence: 99%

“…The lengths of the beams were 500 mm and 300 mm for Li et al [37] and Choi's tests [38], respectively and for applying electric current, the SMA wire were placed from one end to another end, while long fibers may have more convenience to heat, several benefits of reinforcing may be lost; thus, short fibers distributed in matrix have been suggested by numerous researchers [11,40].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the efficiency of induced prestressing in SMA mortar beams through different thermal stimuli

Choi¹,

Ostadrahimi²,

Lee³

et al. 2022

Smart Mater. Struct.

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This paper investigates the efficiency of prestressing effect on the flexural performance of reinforced mortar beams through different heating methods. To this end, different specimens reinforced by 1.0% and 1.5% volume fractions crimped SMA fibers as well as diverse internal and external heating sources are employed. Time-deflection relationships during heating and cooling of specimens are extracted to evaluate the amount of induced prestressing force in each specimen via different heating process. Upon developing prestressing force in the reinforced mortar beams, we carry out several three-point bending tests to study the flexural behavior of mortar beams and compare the material parameters with the reinforced specimens in the absent of prestressing force. The results show that internal heating source using electric current in comparison with external heating via heat gun could be faster and more uniform across the beams cross section contributing to a higher potential capacity in terms of stimulating recovery stress and subsequently boosting ductility and toughness of the composites.

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Section: Geometry and Materials Parameters Of Ni-ti Fibersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the efficiency of induced prestressing in SMA mortar beams through different thermal stimuli

Choi¹,

Ostadrahimi²,

Lee³

et al. 2022

Smart Mater. Struct.

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“…In general, SE SMAs have been employed for selfcentering of RC structures, whereas SMAs with SME have typically been applied to RC structures to introduce prestressing or provide confinement [24][25][26][27]. However, Choi et al [28] used a NiTi SMA with an SME for self-centering in RC beams. They introduced a pre-strain in NiTi SMA wires using cold drawing and then crimped the wire to enhance the bond in the mortar.…”

Section: Introductionmentioning

confidence: 99%

Self-centering capacity of RC columns with smart plastic hinges of martensitic NiTi SMA bars

Choi,

Jeon,

Lee

2023

Smart Mater. Struct.

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The objective of this study was to examine the self-centering capacity of reinforced concrete (RC) columns with martensitic shape memory alloy (SMA) bars in the plastic hinge region. To achieve this, three RC columns were prepared: one was conventional and the other two had SMA bars in the plastic hinge zone. The columns had a diameter of 400 mm, height of 1400 mm, and aspect ratio of 3.5. The 400 mm long SMA bars were connected to the steel rebars using specially devised couplers. A cyclic lateral load was applied at the top of the columns, and the lateral displacements along the height of the columns and the corresponding forces were measured during cyclic lateral loading. The strain in the SMA bars was also measured. The RC column with SMA bars exhibited a plastic hinge around the couplers, thus concrete damage from cracking was concentrated at this site. This was completely different from the failure mode of the conventional RC column. The SMA bars in the column were in an elastic state, whereas the steel rebars yielded inside the couplers. The RC column with SMA bars exhibited excellent self-centering capacity, and its displacement recovery ratio was approximately 95% at a drift of 5%. However, its energy-dissipation capacity was lower than that of the conventional RC column. The equivalent damping ratio of the RC column with SMA bars was approximately 3% after 1.75% drift. It is conjectured that the excellent self-centering of the RC column with SMA bars was caused by the elastic behavior of the martensitic SMA bars.

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“…The shape memory effect of SMAs can provide active confinement and reinforcement to structures due to their high recovery stress (σ re ) when activated thermally. Many studies have investigated the active restraint effect of NiTi-based SMAs on concrete structures, resulting in improved strength and ductility (Choi et al, 2010a, 2010c, 2010d, 2022a, 2022b; El-Hacha and Abdelrahman, 2020; Lee et al, 2021; Li et al, 2008; Suhail et al, 2020a). Researchers have also explored the use of SMAs in conjunction with CFRP to strengthen steel structures, and these studies have demonstrated that the fatigue life of the reinforced steel members can be significantly increased (Abdy et al, 2018; Dawood et al, 2015; El-Tahan et al, 2015; El-Tahan and Dawood, 2018; Li et al, 2020; Taheri-Behrooz et al, 2011; Yuse and Kikushima, 2005; Zheng and Dawood, 2017a; Zheng et al, 2018; Zhou and Lloyd, 2009).…”

Section: Introductionmentioning

confidence: 99%

Enhancement of recovery stress by annealing and prestraining of NiTiNb wires

Yang

Liu

Zhong

et al. 2023

Journal of Intelligent Material Systems and Structures

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NiTiNb shape memory alloy has attracted much attention for its use in prestressing and remedying structural steel and concrete members due to its unique shape memory effect. However, the recovery stress values reported in the literature vary significantly, as the interplay between recovery stress and treatment parameters is not fully understood. In this study, we carefully investigated the effects of annealing and prestraining on the martensitic transformation behavior and mechanical properties of NiTiNb alloy and clarified their correlations to the recovery stress. Our results showed that the yield strength and superelasticity decreased while the ductility and retained stress-induced martensite increased with increasing annealing temperature. We found that high recovery stress can be achieved by annealing the sample above the recrystallization temperature while keeping the annealing temperature as low as possible to maintain high strength. Prestraining the sample to beyond the stress plateau but before yielding was found to be most effective for enhancing the recovery stress. By using these criteria, we were able to obtain large recovery stresses of greater than 550 MPa from 20°C to 200°C through a simple one-step annealing at 700°C and a 10% prestrain using commercial superelastic NiTiNb wire products.

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Enabling shape memory effect wires for acting like superelastic wires in terms of showing recentering capacity in mortar beams

Cited by 15 publications

References 44 publications

On the efficiency of induced prestressing in SMA mortar beams through different thermal stimuli

On the efficiency of induced prestressing in SMA mortar beams through different thermal stimuli

Self-centering capacity of RC columns with smart plastic hinges of martensitic NiTi SMA bars

Enhancement of recovery stress by annealing and prestraining of NiTiNb wires

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