CFS로 휨 보강된 RC부재의 보강겹수에 따른 구조성능 변화

Strengthening method using carbon fiber sheets have been developed for the rehabilitation of structures and applied to the concrete member. However, it is still questionable whether their structural capacity has been well kept without any deterioration as time goes. According to a few inspection results about RC buildings with retrofitted members by CFS, there have been found loss of strengthening using CFS because of the detachment of CFS from the concrete face, which causes the bond failure of CFS. The appearance of this loss may be initiated at just after retrofit construction. And it will be more serious when the layer number of CFS increases. In order to minimize above mistake in retrofit design using CFS, more exact evaluation process to predict the bond loss of CFS is required. The final objective of this research is to propose the guideline and method for estimating resistance capacity of strengthened structure as time goes by. In this paper, as a first step, previous equations to predict flexural strength of member retrofitted by CFS are analyzed and evaluated through a test work. And a nonlinear sectional analysis is performed using a commercial analysis program. In experimental work, specimens with the amounts of carbon fiber and strengthening method as test parameter are tested and their behavior is discussed. From the test, the flexural capacity was not linearly increased even if the layer number of CFS increased when it was more than two. The overall nonlinear behavior of RC member retrofitted with CFS could be suitably predicted by the analytical process in this paper by considering the bond loss.