철계-형상기억합금 바로 제작된 콘크리트 보의 휨 거동
Flexural Behavior of Concrete Beams Reinforced with Fe based Shape Memory Alloy Bar
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초록
본 논문은 철계-형상기억합금(Fe-SMA) 바를 이용하여 제작된 콘크리트 보의 휨 거동 평가를 위한 실험적 연구이다. 실험을 위해 200mm×300mm × 2,200mm의 콘크리트 보를 제작하였으며 인장재로 4% 사전변형된 Fe-SMA 바를 사용하였다. 실험 변수로 인장재 종류(SD400, Fe-SMA), 철근 비(0.2, 0.39, 0.59, 0.78), Fe-SMA 활성화(활성화, 비활성화) 그리고 Fe-SMA bar 연결방법(미연결, 용접, 커플러)를 고려하였다. Fe-SMA 바를 활성화하기 위해 전기저항 가열 방법을 이용하여 5A/mm2의 전류를 실험체가 160℃에 도달할 때 까지 공급하였다. 캠버효과에 의한 실험체의 상향 변위가 안정되면 2,000kN 용량의 엑츄레이터를 이용하여 3점 휨 재하 실험을 실시하였다. 실험결과 Fe-SMA 바를 활성화 함에 따라 캠버효과에 의해 상향 변위가 발생하는 것으로 나타났다. Fe-SMA 바를 활성화한 실험체는 활성화하지 않은 실험체에 비해 더 높은 하중에서 초기균열이 발생하였다. 그러나 일반적인 프리스트레스 콘크리트와 동일하게 Fe-SMA 활성화에 따른 프리스트레스 도입이 보의 극한 상태에 미치는 영향은 미미한 것으로 나타났다.
Abstract
This paper reports an experimental study to evaluate the flexural behavior of concrete beams reinforced using Fe based shape memory alloy (Fe-SMA) bars. For the experiment, a concrete beam of 200mm×300mm×2,200mm was produced, and a 4% pre-strained Fe-SMA bar was used as a tensile reinforcement. As experimental variables, type of tensile reinforcement (SD400, Fe-SMA), reinforcement ratio (0.2, 0.39, 0.59, 0.78), activation of Fe-SMA (activation, non-activation), and joint method of Fe-SMA bar (Continuous, welding, coupler) were considered. The electric resistance heating method was used to activate the Fe-SMA bar, and a current of 5A/mm2 was supplied until the specimen reached 160°C. After the upward displacement of the specimen due to the camber effect was stabilized, a three-point flexural loading experiment was performed using an actuator of 2,000 kN capacity. As a result of the experiment, it was found that the upward displacement occurred due to the camber effect as the Fe-SMA bar was activated. The specimen that activated the Fe-SMA bar had an initial crack at a higher load than the specimen that did not activate it. However, as with general prestressed concrete, the effect of the prestress by Fe-SMA activation on the ultimate state of the beam was insignificant.
참고문헌 (18)
- Abouali, S., "Nonlinear simulation of reinforced concrete beams retrofitted by near-surface mounted iron-based shape memory alloy", Engineering Structures, 187, pp.133~148 (2019)
- Collins, M. P., "Prestressed concrete structures", pp.766~ (1991), Prentice-Hall
- Czaderski. C., "Feasibility of iron-based shape memory alloy strips for prestressed strengthening of concrete structures", Construction and Building Materials, 56(15), pp.94~105 (2014)
- Hong, K. M., "Evaluation of Fe-based shape memory alloy (Fe-SMA) as strengthening material for reinforced concrete structures", Applied sciences, 8(5) (2018)
- 홍기남, "표면매립된 철계-형상기억합금 스트립으로 휨 보강된 RC보의 장기 휨거동", 한국구조물진단유지관리공학회 논문집, 22(3), pp.103~110 (2018), 한국구조물진단유지관리공학회
- 홍기남, "Flexural Response of Reinforced Concrete Beams Strengthened with Near-Surface-Mounted Fe-Based Shape-Memory Alloy Strips", International Journal of Concrete Structures and Materials, 12(5), pp.651~663 (2018), 한국콘크리트학회[DOI]
- Kang, W. H., "A study on development of methods to rehabilitate the damaged prestressed concrete beam using glass fiber", Journal of the Korea Concrete Institute, 11(2), pp.167~175 (1999)
- 김효혜, "균열발생 후 철근부식을 고려한 철근콘크리트 인장부재의 균열거동", 대한건축학회논문집 구조계, 23(9), pp.99~106 (2007), 대한건축학회
- KS, "Standard test method for compressive strength of concrete, KS F 2405", Korean Standard Institute, ~ (2017)
- KS, "Steel bars for concrete reinforcement, KS D 3504", Korean Standard Institute, ~ (2019)
- Lee, W. J., "Recovery stress formation in a restrained Fe–Mn–Si-based shape memory alloy used for prestressing or mechanical joining", Construction and Building Materials, 95(1), pp.600~610 (2015)
- Michels, J., "Mechanical performance of iron-based shape-memory alloy ribbed bars for concrete prestressing", ACI materials journal, 115(6), pp.877~886 (2018)
- Rojob, H., "Self-prestressing using iron-based shape memory alloy for flexural strengthening of reinforced concrete beams", ACI Structural Journal, 114(2), pp.523~532 (2017)
- Sato, A., "Shape memory effect in γ⇄ ϵ transformation in Fe-30Mn-1Si alloy single crystals", Acta Metallurgica, 30(6), pp.1177~1183 (1982)
- Sawaguchi, T., "Development of prestressed concrete using Fe-Mn-Si-based shape memory alloys containing NbC", Materials Transactions, 47(3), pp.580~583 (2006)
- Shahverdi, M., "Iron-based shape memory alloys for prestressed near-surface mounted strengthening of reinforced concrete beams", Construction and Building Materials, 112(1), pp.28~38 (2016)
- Yeon, Y. M, "Evaluation of prestressing effect for Fe-based shape memory alloy", 석사, pp.2018
- Yeon, Y. M., "Long-term behavior of reinforced concrete beams strengthened with near-surface mounted Fe-based shape memory alloy", Journal of the Korean Society for Advanced Composite Structures, 10(4), pp.48~52 (2020)