In this study, the design of anchorage zone for unbonded post-tensioned concrete beam with single tendons of ultimate strength 2400MPa was evaluated to verify that the KDS 14 20 60(2016) and KHBDC 2010 codes are applicable. The experimental results showed that the bursting force equation of current design codes underestimated bursting stress measured by test, because the KDS 14 20 60(2016) and KHBDC 2010 propose the location of the maximum bursting force 0.5h which is the half of the height of member regardless of stress contribution. Although the allowable bearing force calculated by current design codes was not satisfied the prestressing force, the cracks and failure in anchorage zone was not observed due to the strengthening effect of anchorage zone reinforcement.

This paper shows the test results of continuous reinforced concrete beams with external post-tensioning rods. Six three-span beams were prepared and tested to fail. Three beams were designed to have flexure-dominating behavior and the others to have shear-critical behavior. In each group, one beam without external post-tensioning rods was designated as a control beam and two beams had the external post-tensioning rods of 18 mm or 22 mm diameter. External post-tensioning rods were installed within an interior span of 6000 mm. They show V-shaped configuration because two anchorages were located at the top of interior supports and a saddle pin at mid-span was installed at the bottom of the beam. Test results show that the load and shear capacities of strengthened beams were increased when compared with the control beam. Additionally, the measured shear strength was compared with the strength predicted by ACI 318-11 code equations. The detailed ACI 318-11 equation predicted the measured shear strength and failure location of the continuous beam reasonably well.

This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers’ models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.

포스트텐션 프리캐스트콘크리트(Precast Concrete, PC) 보-기둥 접합부에서는 프리스트레스가 도입된 긴장재가 접합부 내부를 관통하기 때문에, 기존의 철근콘크리트(Reinforced Concrete, RC) 보-기둥 접합부와 다른 거동을 나타내며, 포스트텐션 PC 접합부의 정확한 해석 및 설계를 위해서는 먼저 긴장재의 부착특성 및 그에 따른 접합부 거동이 명확히 규명 되어야 한다. 이 연구에서는 포스트텐션 PC 보-기둥 접합부에서 긴장재의 부착특성을 분석하고, 그에 따른 보의 거동 및 파괴모드를 규명함으로써 이를 추후 보-기둥 접합부 모델링에 활용하고자 한다.