표면매립된 철계-형상기억합금 스트립으로 휨 보강된 RC보의 장기 휨거동
Long-term Flexural Behavior of RC Beams Strengthened in Flexure with NSM Fe-SMA Strips
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초록
표면매립공법으로 매립한 철계-형상기억합금으로 보강한 보의 휨 거동을 장기 하중 재하실험을 통해 평가하였다. 철계-형상기억합금 길이대비 2%와 4%의 사전변형 및 형상기억효과 활성화에 의한 프리스트레스 하중 도입을 실험변수로 설정하였다. 1 tonf의 콘크리트 추를보 중앙에 거치한 후 6개월간의 보 중앙부의 장기 처짐을 측정하였다. 실험결과, 철계-형상기억합금으로 보강한 보의 휨 강성이 증대되었으며, 사전변형이 증가할수록 보강재의 강성감소로 인한 처짐이 증가하는 것으로 나타났다. 프리스트레스 하중 도입에 따른 처짐을 비교했을 때, 프리스트레스 하중을 도입하지 않은 실험체에 비해, 프리스트레스 하중을 도입한 실험체는 약 30%의 처짐 감소 효과를 보이는 것으로 나타났다.
Abstract
The long-term flexural behavior of reinforced concrete (RC) beams strengthened with an iron based-shape memory alloys (Fe-SMAs) bya near-surface mounted (NSM) method was evaluated. The pre-strained values of 2% and 4% and introduced prestressing force by an activation ofa shape memory effect of the Fe-SMA strengthening material were considered as experimental variables. Deflections at the center of the RC beamswere measured for six months after the 1 tonf concrete weight was loaded on the beam. Experimental results show that the deflections decreased becauseof the increased flexural stiffness of beams strengthened with the Fe-SMA strips. On the contrary, with increased pre-strained values, the deflectionincreased due to stiffness reduction of the strengthening material. It was confirmed that the specimens incorporating the prestressed force showed thedeflection reduction of about 30%, compared to the ones without the prestressed force.
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