• Journal of Korean Association for Spatial Structures
• /
• v.12 no.3
• /
• pp.89-95
• /
• 2012

Post-tensioned void slab is frequently used for improving the deflection and sound proofing. Two one story 8m spanned structures were built. One structure applied post-tensioned solid slab, but the other did post-tensioned void slab. Dynamic characteristics, which is natural frequency and damping ratio, was compared between that of solid slab and void slab before and after post tension. The natural frequency of void slab was greater than that of solid slab before and after post tension. It was shown that damping ratio of solid slab and void slab was almost same at two stages.

• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.32-32
• /
• 2011

최근 국내외에서 친환경건축물에 관한 관심이 매우 높아짐으로 인해 콘크리트의 물량을 절감하여 이산화탄소량을 줄이는 중공슬래브는 다양한 형태로 세계적으로 개발이 되고 있는 추세이다. 특히 이방향 중공슬래브는 환경적인 측면에서 이방향 중공슬래브는 중공부 생성에 재생플라스틱을 활용하여 폐자원을 재사용하고, 콘크리트와 철근의 사용량 절감에 따른 화석에너지 및 이산화탄소 발생량을 감소한다는 장점이 있다. 또한 시스템 측면에서 이방향 중공슬래브는 기존의 철근콘크리트 플랫플레이트 바닥구조 시스템의 자중을 절감하여 구조체를 경량화 시키고, 이에 따라 장스팬 구현이 가능하며, 단열효과가 뛰어나다. 이와 같이 이방향 중공슬래브는 장점이 많지만 플랫플레이트 슬래브의 취약점인 뚫림전단 파괴에 주의해야 한다. 이에 본 연구에서는 선행으로 실시된 이방향 중공슬래브-기둥 접합부 뚫림전단 성능평가 실험을 바탕으로 하여 경량체가 이방향 중공슬래브-기둥 접합부 뚫림전단 성능에 미치는 영향을 살펴보기 위해 범용 유한요소해석 프로그램인 ABAQUS를 사용하여 경량체량 및 위치를 주요변수로 한 해석적인 변화를 검토하였다. 본 연구를 통해 경량체가 삽입된 이방향 중공슬래브의 뚫림전단 성능에 대해, 해석결과 경량체 량과 위치에 따라 최대 뚫림전단강도는 기준 실험체에 비해 74.3%, 73%의 강도저하를 나타내는 것으로 알 수 있었다. 이는 실험상의 강도저하 값인 84.1%, 56.4%와 다소 차이가 있으며, 해석에서 중공부 주위의 응력집중 현상이 제대로 반영되지 않은 것으로 판단된다. 또한 이방향 슬래브에 경량체를 삽입 할 경우 경량체가 시작하는 부분에서 응력이 급격히 감소하는 현상이 나타났으며, 이러한 급격한 응력감소는 기둥 주위 위험단면의 변화를 가져오는 것으로 추정된다. 즉, 위험단면의 변화는 기둥으로부터 경량체 사이의 거리에 따라 달라지며, 위험단면 내의 콘크리트 단면 손실은 뚫림전단 강도를 감소시킨다. 본 연구에서는 이방향 중공슬래브의 뚫림전단강도를 산정할 수 있는 근사식을 제안하였으며, 보다 정확한 이방향 중공슬래브의 뚫림전단강도의 산정식을 위해서는 위험단면의 변화와 콘크리트 단면손실로 인한 전단강도 저하의 관계에 대한 추가적인 연구가 필요하다.

• Journal of the Korea Concrete Institute
• /
• v.24 no.4
• /
• pp.391-398
• /
• 2012

This paper presents the shear capacities of biaxial hollow slab with donut type hollow sphere. Recently, various types of slab systems which can reduce self-weight of slabs have been studied for increasing constructions of taller and larger building structures. A biaxial hollow slab system is widely known as one of the effective slab system, which can reduce self-weight of slab. According to previous studies, the hollow slab has low shear strength, compared to solid slab. Also, the shear capacities of biaxial hollow slab are influenced by the shapes and materials of hollow spheres. However, the current code does not provide a clear computation method for the shear strength of hollow slab. To verify the shear capacities of this hollow slab, one-way shear tests were performed. Four test specimens were used for test parameters. One was conventional RC slab and others were hollow slabs. The test parameters included two different shapes and materials of plastic balls. The shape parameters were donut and non-donut forms and the material parameters were general plastic and glass fiber plastic. The results showed that the shear strengths varied depending on hollow shapes and materials used in the slab.

• Journal of the Korea Concrete Institute
• /
• v.26 no.5
• /
• pp.643-650
• /
• 2014

Generally, the reinforced concrete slab has great fire resistance performance because concrete has excellent thermal material properties under fire. But, in the case of hollow slab, it will be expected that hollow slabs have different temperature distribution and fire endurance performance compare to reinforced concrete slab. Because hollow slab has internal void space that occurs decreasing regenerative effect of concrete and formation of internal air layer. Evaluation method for fire resistance performance of hollow slabs was proposed using $wickstr{\ddot{o}}m^{\prime}s$ method. For the casual use of evaluation, simplified method was proposed which was limited to solid slab and donut type hollow slab which was developed by authors of this research paper. Also, verification on proposed method was performed by comparing results of fire experiment for hollow slab and evaluation results. Proposed method of the results of this study was possible to predict the residual strength and temperature distribution of slabs under fire.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.6
• /
• pp.97-104
• /
• 2014

Hollow slab is a floor system which reduces the load of vertical structural members and earthquake load by decreasing self-weight of slab. Although hollow slab can reduce self-weight of slab remarkably, flexural strength and shear strength reduce due to the hollow section inside the slab, so it is very important to predict structural behavior. In spite of plenty of domestic and foreign studies on hollow slab, there is a shortage of research on shear performance according to shear reinforcement of one-way hollow slab. Therefore, this study aims to verify the need for shear reinforcement of one-way hollow slab by analyzing failure modes of one-way hollow slab depending on the state of shear reinforcement and comparing shear strengths of estimation formula and experimental value with one another.

• Journal of the Korea Concrete Institute
• /
• v.14 no.2
• /
• pp.156-163
• /
• 2002

Hollow core slabs generally have not been used for a bridge or a parking slab in Korea. In this study, high performance hollow core slabs, which have been the most thick one in domestic are re-designed and examined for practical use. Flexural tests were performed on four 315mm deep hollow core slabs to investigate adaptability for high vehicle live loadings and composite action with topping concrete. The precast slabs were pre-tensioned with ten strands of 1/2 inch diameter at the lower of slab and four strands of 1/2 inch diameter at the upper of slab, and cast with 80 mm deep topping concrete. Tested hollow core slabs showed ductile failure behaviors which were conformed to the current Ultimate Strength Design Method for a span of 10m up to the live load of 1,000 kgf/㎡. The rectangular md round shear cotters which were used for the composite action between precast and topping concrete, developed sufficient strengths because cracking, even micro had not been developed at the end of slabs up to the pure flexural tensile failure.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.458-461
• /
• 2011

이방향 중공슬래브 시스템의 구조특성 및 성능평가 연구의 일부로 실제 건축물에 적용된 이방향 중공슬래브의 연직진동을 측정 및 분석하였다. 캡슐형 경량체를 사용한 이방향 중공슬래브가 적용된 두 건축물에서 바닥 용도상 일상적인 진동발생원이라고 가정할 수 있는 75 kg 성인의 보행, 달리기, 제자리 점프에 대해 슬래브의 연직진동을 측정하였다. 두 대상 건축물은 각각 연구소와 교육시설 용도로 설계 및 건축되었다. 측정된 수직 가속도 데이터로 일본건축학회 환경기준에 (AIJES-2004) 근거하여 진동수 범위 3~30 Hz에 대해 1/3 옥타브 밴드 분석을 실시하였다. 이 분석을 바탕으로 AIJEES-2004에 제시한 기준에 따라 바닥의 연직진동에 대한 거주 성능을 평가한 결과, 측정한 세 건축물에 적용된 이방향 중공슬래브 모두 보행과 달리기에 대해서는 피진동자의 10% 미만이 인지, 제자리 점프에 대해서는 50~70% 미만이 인지할 수 있는 것으로 나타나, 이방향 중공슬래브가 바닥의 연직 진동에 대해 거주 성능이 양호함을 보여주었다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.31-32
• /
• 2010

This paper presents the flexural capacities of one-way hollow slab with donut type hollow sphere. According to analytical studies, the hollow slab with donut type hollow sphere had good flexural capacities such as strength, stiffness and deflection. To verify the flexural capacities of this hollow slab, flexural tests were performed on the one-way hollow slabs.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.1
• /
• pp.126-133
• /
• 2017

This paper presents the shear capacities of hollow slab with plate and octagonal pillar type hollow sphere. Recently, the interest in precast hollow slab system for buildings is growing up according to the demand for high quality control and the increase in slab thickness. A hollow slab system is widely known as one of the effective slab system which can reduce self-weight of slab. However, hollow slabs are vulnerable to the deterioration in the shear strength due to the decrease of concrete at slab web which resists shear. Especially, in case of precast hollow slabs, it has joint surface between precast concrete slab modules along transverse axis of slab, and shear failure, that is caused by cracks at joints, has to be prevented. Therefore, in this study, shear capacity of the I-slab system is evaluated by 3-points-supported shear test along the longitudinal and transverse axis of slab specimen. Test results showed that I-slab had enough shear strength compared to theoretical shear strength even if it included the joint surfaces.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.69-70
• /
• 2010

This paper presents the flexural capacities of one-way hollow slab with materials. To verify the flexural capacities of this hollow slab, flexural tests were performed on the one-way hollow slabs. The test parameters included two different materials of plastic balls. The material parameters were general plastic and glass fiber plastic.