철계-형상기억합금 나선철근으로 횡구속된 콘크리트의 압축거동 = Compression Behavior of Concrete Laterally Confined by Fe-Based Shape Memory Alloy Spiral Reinforcement

국문 초록 (Abstract)

본 논문은 철계형상기억합금(Fe-SMA) 나선철근을 이용한 기둥의 횡구속 효과를 평가한 실험적 연구를 보고한다. 실험을 위해 사전변형 4%의 5mm × 5mm의 Fe-SMA 나선철근으로 구속된 150mm × 150mm ×300mm의 원형 실험체가 제작되었다. 실험변수는 Fe-SMA 나선철근의 피치(0mm, 80mm, 60mm, 40mm), Fe-SMA 나선철근의 활성화 유무(활성화, 비활성화)를 고려하였다. Fe-SMA 나선철근 활성화를 위해 소성로를 사용하여 목표온도 140℃까지 가열하였다. 실험체의 온도가 상온에 도달한 후 만능재료시험기를 이용하여 1축 압축실험을 실시하였다. 실험결과를 통해 Fe-SMA 나선철근을 활성화하여 능동적 횡구속압이 작용된 실험체의 최대응력과 최대응력 발현 시의 변형률은 활성화하지 않은 실험체에 비해 크게 증가하는 것으로 나타났다. 또한, 나선철근 피치의 감소로 인해 능동적 구속압이 증가함에 따라 최대응력과 연성지수가 크게 증가하는 것으로 나타났다. 특히 보강 간격이 40mm인 활성화된 나선철근으로 구속된 실험체는 최대하중 도달 후 하중이 유지 및 증가하는 변형경화가 발생하는 것으로 나타났다.

다국어 초록 (Multilingual Abstract)

This study evaluates the lateral confinement effect of a column using Fe-based shape memory alloy (Fe-SMA) spiral reinforcement. For the experiment, 150 × 150 × 300-mm cylinder specimens confined by Fe-SMA spiral reinforcement of a 4% pre-deformed 5 × 5-mm section were fabricated. Two experimental variables were considered: the pitch (0, 80, 60, and 40mm) and activation/non-activation of the Fe-SMA spiral reinforcement. To activate the Fe-SMA spiral reinforcement, the specimen was heated to the target temperature of 140° using a kiln. After the specimen was cooled to room temperature, a uniaxial compression test was performed using a universal testing machine. The experimental results confirm that the maximum stress and corresponding strain of the specimen with Fe-SMA spiral reinforcement activation were significantly increased compared with that of the specimen without activation. Additionally, it was found that, due to the decreased pitch of the spiral reinforcement, the maximum stress and ductility index increased significantly as the active lateral confinement pressure increased. In particular, it was found that the specimens confined by activated 40-mm-pitch spiral reinforcement exhibited strain hardening, which maintained and increased the load after the maximum load was reached.

참고문헌 (Reference)

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