The BX composite beam is designed to have the same cross-section regardless of the size of the momentum, which is a disadvantage of the existing steel structure. Combination of the H-beam end compressive material and the H-section steel tensile reinforcement according to the moment size in a single span, It is possible to say that it is an excellent synthesis which increases the performance. When underground and overhead structures are constructed, it is possible to reduce the bending, increase lateral stiffness, reduce construction cost, and simplify joints. The seamability of the joining part is a simple steel composite beam because of the decrease of the beam damping at the center of the beam and the use of the end plate of the new end compressing material. In the case of structures with long span structure and high load, it is advantageous to reduce the material cost by designing large steel which is high in price at less than medium steel.

Recently, practical application of high tension bar is attempted. The main object of using high tension bar is strengthening of material property and decreasing of steel amount. If using high tension bar which is not a definite yield strength，according to strain ratio of high tension bar tensile and compressive dominate mode ciearly, there being a possibility dividing becoming difficult. Specially, Providing steel ratio of balanced destruction is very difficult. In this study, high tension bar to apply to flexural member and the behavior experiment bending after one, will consider high tension bar the application possible standard of existing.

In this study, the 1-directional tension tests were conducted to evaluate ductility capacity of splice rebar. As a result, the ductility of the reinforced concrete members embedded in the coupler was significantly lower than that of general RC members.

본 연구의 목적은 국내 콘크리트구조설계기준 부록에 새롭게 포함된 CEB-FIP Model Code 1990 균열폭 산정식을 콘크리트 강도를 변수로 하여 평가하는 것에 있다, 평가 도구로 부착응력-미끌림 관계를 적용하여 구축한 균열요소모델과 기존 연구자들의 실험결과로부터 얻은 균열폭을 사용하였으며 기존 실험결과와 비교 평가함으로 검증하였다. 평가대상인 MC-90의 균열폭 산정식의 증요변수는 인장증강효과와 평균부착응력이며 이들을 균열요소모델 해석결과와 비교함으로 강도에 따라 개선된 인장증강효과와 평균부착응력을 제안하였다.