띠철근이 철근 콘크리트 사각형 기둥의 강도와 연성에 미치는 영향

Abstract

본 논문에서 띠철근이 철근 콘크리트 사각형 기둥의 강도와 연성에 미치는 영향을 실험을 통하여 연구하여 다음과 같은 결론을 얻었다. 1. 띠철근 콘크리트 기둥에 대한 실험결과, 띠철근의 간격이나 형상이 콘크리트 기둥의 극한강도에 미치는 영향은 매우 적은 것으로 판단된다. 2. 띠철근의 간격과 형상은 사각형 콘크리트 기둥의 연성에 대해 큰 영향을 미치며, 이는 극한 상태에서 안전성에 커다란 영향을 미칠 것으로 판단된다. 3. 띠철근 콘크리트 기둥에서 띠철근의 간격이 좁을수록 연성이 증가하여 지연파괴가 발생함으로서 안전성이 증대할 것으로 판단된다. 4. 단순 겹이음된 띠철근 사각형 콘크리트 기둥은 표준 폐합 띠철근 기둥에 비해 연성이 매우 낮아 극한 파괴시 안전성이 감소된다. 따라서 시공상의 용이성으로 단순 겹이음된 띠철근 사용은 지양되어야 한다. 5. 갈고리로 겹이음된 띠철근 기둥은 표준 폐합 띠철근 기둥과 비슷한 연성을 나타낸다. 따라서 시공시 표준 폐합 띠철근의 사용이 매우 곤란한 경우, 충분한 성능 검토 후 대체 사용할 수도 있을 것으로 판단된다.

The purpose of this study is to evaluate the influence and safety that the interval and shape of tie has on the strength and ductility of ferroconcrete square pillar with experiment. Previous studies reported that a tie effectively promoted the safety by improving the strength and ductility of pillar through suitable restriction of core concrete and the horizontal direction support of compression bar. There is the standard of the shape and reinforcement of tie for ferroconcrete pillar, but nevertheless currently a tie used in some fields under construction has been constructed in different way from the design for the convenience of construction. A research was required to analyze the problem on the behavior of concrete pillar caused from a shoddy and fault construction of tie, and then evaluate the safety. Accordingly, this study selected the interval and shape as major influential factor, then evaluated its influence on the strength and ductility with experiment. The method of droop using load-deflection curve from experiment and the method by the transformative energy were used to evaluate the ductility ratio. As the result of this experiment, the ultimate strength of each testing body was almost similar each other, so it is considered that there is insignificant influence that the interval or shape of tie had on the ultimate strength. For the influence of tie, the ductility is increased as its interval is narrower, and the safety is increased owing to delayed fracture. Square concrete pillar with simple double-joint tie used in some fields under construction owing to the easiness of construction had much lower ductility as compared with standard closure tie pillar, thus its safety was reduced during ultimate fracture, so it must be sublated. On the other hand, tie pillar doubly jointed with a hook had the ductility similar with that of standard closure tie pillar. Therefore it is considered that if it is very difficult to use standard closure tie when constructing, we can substitute other tie for this after sufficient investigation of efficiency.