Shear load tests on cast-in High-Shear Ring Anchor (HRA) installed on the sides of slabs were conducted to investigate the structural behavior of concrete breakout. The test variables include slab thickness, anchor location, and placement of anchor reinforcement. All specimens showed concrete breakout failure. Test results show that inclined cracks initiated at both sides of ring at the level of anchor center in the specimens without anchor reinforcement. In the specimens with anchor reinforcement, the cracks started at the hooks of the anchor reinforcement and, therefore, the projected area of the failure surface was enlarged. Due to the large contact area between ring and concrete and the high-shear stiffness of the ring, maximum loads of all specimens developed before displacement of ring reached 2 mm. By placing anchor reinforcement, projected area of failure surface in direction perpendicular to anchor axis as well as edge distance ca1 were enlarged and the maximum loads increased by 64.3 and 127 % for h150 and h210 specimens, respectively. The average of the test-to-prediction ratios was 1.11 with a coefficient of variation of 13.2 %, when the predicted values were calculated using the existing equation with the measured concrete strength. In the test results, it was found that the concrete breakout strength of HRA can be safely predicted using the existing equation.
얇은 슬래브 측면에 선설치된 고전단링앵커의 콘크리트파괴 거동을 평가하기 위하여 슬래브 두께, 앵커 설치 위치, 앵커철근 유무를 변수로 전단 실험을 수행하였다. 모든 실험체는 콘크리트파괴가 발생되었으며, 앵커철근이 배치되지 않은 실험체에서 균열은 앵커 중심 위치의 링외부에서 시작하여 경사지게 발생하였다. 앵커철근이 배치된 실험체는 앵커철근 정착부 갈고리 부근에서 균열이 시작되어 앵커철근이 없는 동일 실험체에 비해 파괴 영역이 확대되었다. 고전단 링앵커는 강재 링과 콘크리트의 접촉면적이 넓고 강재 링의 전단강성이 높기 때문에 2 mm 수평 변위 이전에 최대 내력이 발현되었다. 앵커철근을 배치한 실험체는 가력방향 연단거리(ca1)의 증대뿐 아니라 슬래브 폭 방향으로 파괴 영역의 확대효과가 있어, 앵커철근이 없는 h150, h210 실험체 대비 각각 64.3 %, 127 % 증가하였다. 실험일 콘크리트압축강도를 사용한 평균 콘크리트파괴강도 예측식과 실험값을 비교한 결과, 실험강도/예측강도 비의 평균은 1.11, 변동계수를 13.2 %였다. 따라서 기존 평가식을 이용하여 안전하게 고전단 링앵커 강도 평가가 가능하였다.
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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 :3-10