This paper presents the test results on 5 UHPFRC-RC two-way slab-column connections to investigate retrofitting effect of section enlargement using ultra-high performance fiber reinforced concrete (UHPFRC) on punching shear capacity. The test parameters were the section enlargement thickness and the amount of steel re-bar in it. Sand blasting method was conducted to roughen the interface. The test results showed that by adding a thin layer of UHPFRC, considerable increases in global punching shear resistance and structural rigidity were achieved. Furthermore, although it is noticeable that two governing cracking patterns (diagonal tensile cracking in RC section, near interface cracking) were observed, all the composite slabs appeared to experience punching shear mode due to propagation of diagonal tensile cracking. The test results were compared with predicted strength by refined code provisions using equivalent design parameters. The comparison results showed that the refined code provisions addressed comparatively good prediction of the test results with reasonable safety margin.
본 연구에서는 초고성능 섬유보강 콘크리트(UHPFRC)를 사용한 단면증대 보강 효과를 검증하기 위해 총 5개의 이방향 슬래브-기둥 접합부의 뚫림 전단 실험을 수행하였다. 실험 변수는 단면증대 두께와 UHPFRC 내 배근 철근비이며, 계면은 샌드 블라스팅 공법을 통해 면처리하였다. 실험 결과, 단면증대 공법을 통해 UHPFRC-RC 이방향 슬래브-기둥 접합부의 최대 전단 내력과 구조적 강성이 크게 증대되었다. 특히 거동을 지배하는 두 가지 주요 균열 패턴(RC 단면의 사인장 균열, 계면 전단 균열)이 관측되었지만, 실험 분석 결과 모든 보강 실험체는 사인장 균열 진전으로 인한 뚫림 전단 모드로 파괴된 것으로 판단된다. 단면증대 공법을 통한 보강 효과를 반영하기 위해 등가 설계 변수를 적용하여 수정된 현행 설계 기준식에 의한 예측 강도를 실험 결과와 비교하였다. 비교 결과, 수정된 현행 설계 기준은 실험 결과를 비교적 안전측으로 잘 예측하였다.
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- Publisher :Korea Concrete Institute
- Publisher(Ko) :한국콘크리트학회
- Journal Title :Journal of the Korea Concrete Institute
- Journal Title(Ko) :콘크리트학회 논문집
- Volume : 31
- No :1
- Pages :29-40