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비부착 표면매립 긴장보강된 철근 콘크리트 보의 거동 분석
정우태 ( Jung Woo-tai ),박종섭 ( Park Jong-sup ),강재윤 ( Kang Jae-yoon ),박희범 ( Park Hee Beom ),김상현 ( Kim Sang-hyun ) 한국복합신소재구조학회 2020 복합신소재구조학회논문집 Vol.11 No.6
본 논문은 콘크리트 구조물 보강공법 중 하나인 CFRP 표면매립 긴장보강의 거동을 분석하였다. 이를 위해 CFRP 긴장재 및 긴장시스템을 개발하고 손상후 보강거동 및 충전재 유무에 따른 비부착 보강거동을 고찰하였다. 실험결과, 비부착 실험체의 보강효과는 무보강 실험체보다 38% 증가하지만, 부착 실험체보다 17% 감소하였다. 손상된 콘크리트를 보강한 경우는 건전한 콘크리트의 보강효과와 유사했다. 정착장치와 부착된 CFRP 긴장재는 안정된 보강효과를 보였다. Carbon fiber reinforced polymer (CFRP) strengthens concrete structures due to its corrosion resistance. Various structural strengthening methods have been developed and applied to strengthen deteriorated reinforced concrete structures, such as externally bonded reinforcements (EBRs) and near surface mounted (NSM) systems. However, both EBR and NSM reinforcement demonstrate premature failure. Recent research has attempted to prestress NSM reinforcement, but this requires a special prestressing system and various strengthening behaviors without filler. Therefore, this study develops a CFRP tendon and prestressing system for NSM reinforcement and investigates the strengthening effect considering the unbonded performance without filler and the damaged concrete. The test results reveal that the unbonding of the CFRP tendon improves the strengthening effect by 38%; however, it remains 17% less strong than the bonded specimen. The strengthening effect of the damaged concrete is similar to that of the general strengthened specimen. The use of a CFRP tendon with filler and anchorage system appears to improve stable strengthening behavior.
콘크리트와 탄소섬유쉬트의 부착파괴 거동에 관한 실험적 연구
정우태 ( Jung Woo-tai ),박종섭 ( Park Jong-sup ),유영준 ( You Young-jun ),박홍석 ( Park Hung-seok ) 한국구조물진단유지관리공학회 2001 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.5 No.2
Carbon Fiber Sheet(CFS) is widely used to strengthen deteriorated concrete structures. Generally bond strength between concrete and CFS is important, because of enhancing bond of CFS. Therefore if bond strength is sufficient, expect to enhance reinforcement effect. Unless sufficient, expect not to enhance reinforcement effect, because of occurring bond failure between concrete and CFS. Bond failure of flexural reinforced structures using CFS is due to shear strength between concrete and CFS. Therefore Japanese standard about Fiber Reinforcement has rules of designing bond length by the design bond strength, which is used shear strength between concrete and CFS. In this study consider bond failure behavior between concrete and CFS by bond stress between concrete and CFS and carry out the pure shear bond strength test between concrete and CFS for bond strength design used to estimate bond length on CFS design.
정우태(Jung, Woo-Tai),장승호(Jang, Seung-Ho),고효인(Kho, Hyo-In) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.11
열차 운행시에 발생하는 전동소음은 열차 차륜과 레일 표면조도의 불균일성에 의하여 가진된 진동에 의해 발생된다. 따라서 열차 전동소음의 전달, 예측 및 분석을 위해서는 차륜과 레일표면의 음향조도(acoustic roughness)의 정확한 측정과 분석이 필요하다. 그러나 현재의 레일표면의 조도측정을 위한 장치와 방법은 작업자의 수작업에 의존한 트롤리 장치를 사용 함으로써, 불일정한 측정속도와 흔들림과 같은 불안정한 인터페이스를 야기하여 측정값의 오차와 외란을 증대시키는 단점을 지닌다. 본 논문은 철도궤도의 레일상에서 자율 정속 주행하면서 레일표면의 음향조도를 측정하는 자동화 측정장치 및 플랫 폼을 개발함으로써, 측정정밀도를 향상시키고 측정값의 불균일성을 감소시켰다. 또한 측정값의 신뢰도와 정확도 향상을 위해 동일한 복수의 변위센서 적용법을 제안하였으며 표준레일구간의 현장측정을 통해 동일 변위센서로부터 융합된 데이터의 정 확성을 검증하였다. Rolling noises during train operation are caused by vibration excited from irregularities of surface roughness between wheel and rail. Therefore, a proper measurement and analysis techniques of acoustic roughness between wheel and rail surface are required for transmission, prediction, and analysis of the train rolling noise. However, since current measuring devices and methods use trolley-based manual handling devices, the measurements induce unstable measuring speed and vibrational interface that increases errors and disturbances. In this paper, a new automatic rail surface exploring platform with a speed controller has been developed for improving measurement accuracy and reducing inconsistency of measurements. In addition, we propose a data integration method of the rail surface roughness with multiple homogeneous displacement sensors and verified the accuracy of the integrated data through standard test-bed railway track investigation.
탄소섬유쉬트로 보강된 철근콘크리트 보의 휨강도 예측식 제안
정우태 ( Jung Woo-tai ),박종섭 ( Park Jong-sup ),유영준 ( You Young-jun ),박영환 ( Park Young-hwan ) 한국구조물진단유지관리공학회 2004 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.8 No.1
Recently, Carbon Fiber Reinforced Polymer (CFRP) sheets are widely used to strengthen the deteriorated reinforced concrete (RC) beams. Although many tests were carried out to verify the flexural capacity of RC beams strengthened with CFRP sheets, the behavior and flexural strength of strengthened RC beams are not clearly investigated yet. The objective of this study is to develop a new equation with additional strength reduction factor which can predict the flexural strengthening effect of RC beams strengthened with CFRP sheets. The regression factors of this proposed formula were determined through the multiple linear regression analysis. It is shown that the proposed formula agrees well with the experimental data compared to other previous formulas.
다양한 표면형상에 따른 FRP 보강재의 부착특성 실험연구
정우태(Jung Woo Tai),박영환(Park Young Hwan),박종섭(Park Jong Sup) 대한토목학회 2011 대한토목학회논문집 A Vol.31 No.4A
FRP 긴장재는 PS 강연선의 부식 문제를 해결하기 위한 대안으로써 사용될 수 있으며, FRP 긴장재의 재료특성(부착강도, 인장강도, 전달길이 등)은 구조물에 적용하기 위해서 결정되어야 한다. 재료특성 중에 부착은 FRP 긴장재로 긴장된 PSC 구조물에 적용하기 위해 명확하게 요구되어야 한다. 이 연구는 다양한 표면형상을 갖는 FRP 보강재의 부착특성을 연구하였다. 콘크리트의 철근과 강연선 대신에 사용되는 FRP 재료의 부착특성을 결정하기 위해 CAN/CSA S806-02에서 제안된 직접인발 시험을 수행하였다. 강연선, 이형 철근, 6가지 다른 표면 형상을 갖는 탄소 또는 유리섬유 FRP 보강재에 대하여 총 40개의 시편이 제작되었다. 부착실험 결과 각 실험체의 다양한 부착응력-슬립 곡선을 나타냈고, 국내에서 제작된 CFRP 긴장재의 부착특성과 비교하였다. FRP (Fiber Reinforced Polymer) tendons can be used as an alternative to solve the corrosion problem of steel tendons. Material properties of FRP tendons-bond strength, transfer length, development length-must be determined in order to apply to concrete structures. First of all, in case of application for pretension concrete members with CFRP tendons, transfer length is an important characteristic. The bond of the material characteristics should be demanded clearly to apply to PSC structures prestressed with FRP tendons. This paper investigated on the bond characteristics of FRP reinforcements with various surface-type. To determine the bond characteristics of FRP materials used in place of steel reinforcement or prestressing tendon in concrete, pull-out testing suggested by CAN/CSA S806-02 was performed. A total of 40 specimens were made of concrete cube with steel strands, deformed steel bar and 6 different surface shape FRP materials like carbon or E-glass. Results of the bonding tests presented that each specimen showed various behaviors as the bond stress-slip curve and compared with the bond characteristic of CFRP tendon developed in Korea.