• 콘크리트학회논문집
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• 제18권3호
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• pp.321-330
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• 2006

노후화된 철근콘크리트 공동주택을 리모델링할 경우에 거주성의 향상을 위하여 기존 바닥판에 새로운 바닥판을 신설하여 기존 건물의 평면을 확장시키는 경우가 많다. 새로운 바닥판이 기존 바닥판에 연결될 경우에 두 바닥판의 접합 방법에 따라서 힘의 흐름이 달라진다. 이 연구에서는 8개의 부분 실험체와 24개의 전체 실험체를 제작하여 3종류의 강절점으로 연결된 바닥판 접합부의 파괴모드와 내력을 실험적으로 평가하였다. 실험체의 주요변수는 강절점 접합방식, 철근의 묻힘 깊이(0, 50, 60, 100, 120mm), 묻힘 길이(100, 200, 300mm), 철근의 배근 간격(150, 200, 300, 450mm)이다. 실험에서 강절점으로 연결된 바닥판의 휨내력은 일체화된 바닥판의 철근항복시의 내력과 유사하였다.

• International Journal of Concrete Structures and Materials
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• 제11권1호
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• pp.161-169
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• 2017

Flat slab systems are vastly used in multi-story buildings because of their savings in story height and construction time, as well as for their flexibility in architectural remodeling. However, they frequently suffer brittle punching-shear failure around columns, especially when subjected to lateral loads. Therefore, seismic codes labeled flat slabs as non-ductile systems. This research goal is investigating some construction alternatives to enhance flat slab ductility and deformability. The alternatives are: adding different types of punching-shear reinforcement, using discreet fibers in concrete mixes, and increasing thickness of slab around columns. The experimental study included preparation and testing of seven half-scale interior slab-column connections up to failure. The first specimen is considered a reference, the second two specimens made of concrete mixes with different volumetric ratios of polymer fibers. Another three specimens reinforced with different types of punching-shear reinforcement, and the last specimen constructed with drop panel of inverted pyramidal shape. It is found that using the inverted pyramid-shape drop panel of specimen, increases the punching-shear capacity, and the initial and the post-cracking stiffnesses. The initial elastic stiffnesses are different for all specimens especially for the slab with closed stirrups where it is experienced the highest initial stiffness compared to the reference slab.

• 한국지진공학회논문집
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• 제26권3호
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• pp.137-147
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• 2022

This study investigated the seismic performance of reinforced concrete (RC) wall-slab frames with masonry infills. Four RC wall-slab frames with or without masonry infill were tested under cyclic loading. The RC frames were composed of in-plane and out-of-plane walls and top and bottom slabs. For masonry infill walls, cement bricks were stacked applying mortar paste only at the bed joints, and, at the top, a gap of 50 mm was intentionally left between the masonry wall and top RC slab. Both sides of the masonry walls were finished by applying ordinary or fiber-reinforced mortars. The tests showed that despite the gap on top of the masonry walls, the strength and stiffness of the infilled frames were significantly increased and were different depending on the direction of loading and the finishing mortars. During repeated loading, the masonry walls underwent horizontal and diagonal cracking and corner crushing/spalling, showing a rocking mode inside the RC wall-slab frame. Interestingly, this rocking mode delayed loss of strength, and as a result, the ductility of the infilled frames increased to the same level as the bare frame. The interaction of masonry infill and adjacent RC walls, depending on the direction of loading, was further investigated based on test observations.