Recovery stress of shape memory alloy wires induced by hydration heat of concrete in reinforced concrete beams

Choi, Eunsoo; Hu, Jong Wan; Lee, Jong-Han; Cho, Baik-Soon

doi:10.1177/1045389x13519005

Cited by 21 publications

(8 citation statements)

References 14 publications

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“…The degree of cold-work of the wires was 6.88%, which is defined as the percentage of reduction in the cross-sectional area. The tensile behavior of the cold-drawn SMA wire was reported in a previous paper as shown in figure 1 (Choi et al 2015a). The cold-drawn SMA wire showed elastic and plastic behavior, which was totally different from the as-received SMA wire, which showed four states of behavior: elastic, transition from twined to detwined state, elastic again, and plastic behavior.…”

Section: Sma Fibersmentioning

confidence: 76%

“…Both methods may be inconvenient for manufacturing and installation. There was a trial of using hydration heat of concrete to induce the shape memory effect of SMA bars in concrete beams, but it appears that the study left a few issues unresolved (Choi et al 2015a). When superelastic SMA fibers are used in concrete beams, cracks are closed immediately when loading is removed.…”

Section: Introductionmentioning

confidence: 99%

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Repairing cracks developed in mortar beams reinforced by cold-drawn NiTi or NiTiNb SMA fibers

Choi

Kim

Youn

et al. 2015

Smart Mater. Struct.

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In this study, mortar beams reinforced by shape memory alloy (SMA) fibers of NiTi and NiTiNb alloys were prepared to perform crack-repairing tests using three-point bending tests. The SMA fibers had a length of 30 mm, and their types were straight, dog-bone, and dog-bone with paper wrapping. For the bending tests, twelve types of mortar beams with the dimensions of 40 mm×40 mm×160 mm (B×H×L) were prepared. Half of them had a top steel reinforcement, and equal numbers of beams were assigned to the NiTi and NiTiNb fibers. Five SMA fibers were located at the bottom center of the beams along with an artificial crack of 10 mm depth and 1 mm thickness. Epoxy was used to fill the cracks to bond the cracked surfaces using injection, and a hot-gun was used to heat the SMA fibers in the cracks. The crack widths were measured before and after the cracks were repaired, and force-displacement curves were obtained to assess the flexural strength recovery ratio of the beams. It does not appear that the crack-closing capacity of SMA fibers is a crucial factor to recover the flexural strength in repaired beams. However, adequate application of epoxy is critical for repairing cracks, and the residual stress of SMA fibers seems to contribute to increase flexural strength of repaired beams. The residual stress of SMA fibers functions as prestress on mortar and delays the initiation of cracking.

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Section: Sma Fibersmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Repairing cracks developed in mortar beams reinforced by cold-drawn NiTi or NiTiNb SMA fibers

Choi

Kim

Youn

et al. 2015

Smart Mater. Struct.

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“…In addition, SMA processed good energy dissipation capability, corrosion resistance and long fatigue life. The advantageous properties of SMA have been applied in construction engineering, such as SMA wire reinforced concrete [11] and SMA fiber reinforced concrete. [12] Song et al [13] proposed the concept of Intelligent Reinforced Concrete (IRC) based on the shape memory effect of SMA wire.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Crack Recovery Behavior of Engineered Cementitious Composite (ECC) Incorporated Memory Alloy Fiber at Low Temperature

Song¹,

Wang²,

Yuan³

et al. 2022

ES Mater. Manuf.

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Traditional cement-based materials are brittle materials with poor toughness and easy cracking characteristics. The formation of cracks due to drying shrinkage and external load accelerated the destruction of building structures. In order to improve brittleness of concrete, engineered cementitious composites (ECC), a fiber reinforced cement-based composite with high ductility and features of multiple cracking, was proposed and had attracted fully attention. Nickel-Titanium (Ni-Ti) alloy fiber had better crack recovery capabilities compared to steel fiber. Therein, Ni-Ti alloy fiber, activated at low temperature, was applied to endow ECC with the function of crack recovery in a short period. Crack recovery performances were investigated by measuring the crack width, water permeability and acoustic emission analysis. Results showed that the flexural strength, compressive strength of ECC was enhanced by adding Ni-Ti alloy fiber and specimens displayed features of multiple cracking. Further, the crack width was reduced after 45℃ heat treatment when incorporated Ni-Ti alloy fibers. Moreover, shape memory effect of Ni-Ti alloy fibers that activated and recovered at a low heat treatment temperature of 45 ℃ was verified.

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“…To overcome these problems, concrete or cement composites with shape memory alloys (SMAs) are proposed and considered as smart composites that can generate recovery stress of SMAs due to the shape memory effect (SME) to provide pre-stress or crack-curing capacity in cement composites. This has been investigated by many studies (Czaderski et al 2014, Choi et al 2014a, Shajil et al 2012.…”

Section: Introductionmentioning

confidence: 99%

Crack-closing of cement mortar beams using NiTi cold-drawn SMA short fibers

Choi

Kim

Chung

et al. 2014

Smart Mater. Struct.

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In this study, crack-closing tests of mortar beams reinforced by shape memory alloy (SMA) short fibers were performed. For this purpose, NiTi SMA fibers with a diameter of 0.965 mm and a length of 30 mm were made from SMA wires of 1.0 mm diameter by cold drawing. Four types of SMA fibers were prepared, namely, straight and dog-bone-shaped fiber and the two types of fibers with paper wrapping in the middle of the fibers. The paper provides an unbonded length of 15 mm. For bending tests, six types of mortar beams with the dimensions of 40 mm × 40 mm × 160 mm (B×H×L) were prepared. The SMA fibers were placed at the bottom center of the beams along with an artificial crack of 10 mm depth and 1 mm thickness. This study investigated the influence of SMA fibers on the flexural strength of the beams from the measured force-deflection curves. After cracking, the beams were heated at the bottom by fire to activate the SMA fibers. Then, the beams recovered the deflection, and the cracks were closed. This study evaluated crack-closing capacity using the degree of crack recovery and deflection-recovery factor. The first factor is estimated from the crack-width before and after crack-closing, and the second one is obtained from the downward deflection due to loading and the upward deflection due to the closing force of the SMA fibers.

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Recovery stress of shape memory alloy wires induced by hydration heat of concrete in reinforced concrete beams

Cited by 21 publications

References 14 publications

Repairing cracks developed in mortar beams reinforced by cold-drawn NiTi or NiTiNb SMA fibers

Repairing cracks developed in mortar beams reinforced by cold-drawn NiTi or NiTiNb SMA fibers

Investigation on Crack Recovery Behavior of Engineered Cementitious Composite (ECC) Incorporated Memory Alloy Fiber at Low Temperature

Crack-closing of cement mortar beams using NiTi cold-drawn SMA short fibers

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