• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.182-189
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• 2021

VPS(Void Plywood Slab System, VPS) has optimized the shape of the hollow material. In addition, it has a function to prevent the floating of the hollow material and the separation due to the working load. In this study, the punching shear capacity of flat plate was performed using Void Plywood Slab System with form work panel proposed in the previous study. As a result of the test, the strength of the VSPS specimen in which the hollow material was placed beyond 2.0 times the column width from the loading point was reduced by 9.4% compared to the reference specimen. However, the strength value was about 1.57 times higher than the design value suggested by KBC 2016. It was found that there was no change in stiffness compared to the reference specimen until shear failure occurred in the VSPS specimen in which the hollow material was placed. It can be seen that this experiment is being destroyed by shear as the flexural reinforcing bars are sufficiently reinforced.

• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.231-243
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• 2021

In this paper, a dynamic response mapping model of the wheel-rail system is established by using the support vector regression (SVR) method, and the hierarchical safety thresholds of the subgrade void are proposed based on the reliability theory. Firstly, the vehicle-track coupling dynamic model considering the subgrade void is constructed. Secondly, the subgrade void area, the subgrade compaction index K30 and the fastener stiffness are selected as random variables, and the mapping model between these three random parameters and the dynamic response of the wheel-rail system is built by using the orthogonal test and the SVR. The sensitivity analysis is carried out by the range analysis method. Finally, the hierarchical safety thresholds for the subgrade void are proposed. The results show that the subgrade void has the most significant influence on the carbody vertical acceleration, the rail vertical displacement, the vertical displacement and the slab tensile stress. From the range analysis, the subgrade void area has the largest effect on the dynamic response of the wheel-rail system, followed by the fastener stiffness and the subgrade compaction index K30. The recommended safety thresholds for the subgrade void of level I, II and III are 4.01㎡, 6.81㎡ and 9.79㎡, respectively.

• Journal of Korean Society of Steel Construction
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• v.24 no.3
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• pp.313-323
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• 2012

The purpose of this study is to evaluate $CO_2$ reduction and the flexural performance of steel wire-integrated void deck plate slabs that were inserted in omega-shaped steel plates to reduce concrete and welded H-section beams. The void deck plate slab can secure the structure, not only reducing the weight of the building but it is also eco-friendly. Therefore, this study evaluated the flexural performance of the composite beam by conducting a monotonic loading test with the use of actuators. It quantitatively evaluated the $CO_2$ emission based on earlier studies. The main test parameters are the concrete thickness of upper slabs, and the interrupted width of the omega-shaped steel plate. The result of the test showed that the welded H-section beam applied steel wire-integrated void deck plate slabs that were inserted into the omega-shaped steel plate declined in flexural performance on the composite beam after reducing concrete volume. Likewise, it is effective in reducing $CO_2$.

• Journal of Korean Association for Spatial Structures
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• v.9 no.4
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• pp.5-10
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• 2009

• Nuclear Engineering and Technology
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• v.45 no.5
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• pp.613-624
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• 2013

Multi-dimensional two-phase phenomena occur in many industrial applications, particularly in a nuclear reactor during steady operation or a transient period. Appropriate modeling of complicated behavior induced by a multi-dimensional flow is important for the reactor safety analysis results. SPACE, a safety analysis code for thermal hydraulic systems which is currently being developed, was designed to have the capacity of multi-dimensional two-phase thermo-dynamic phenomena induced in the various phases of a nuclear system. To validate the performance of SPACE, a two-dimensional two-phase flow test was performed with slab geometry of the test section having a scale of $1.43m{\times}1.43m{\times}0.11m$. The test section has three inlet and three outlet nozzles on the bottom and top gap walls, respectively, and two outlet nozzles installed directly on the surface of the slab. Various kinds of two-dimensional air/water flows were simulated by selecting combinations of the inlet and outlet nozzles. In this study, two-dimensional two-phase void fraction profiles were quantified by measuring the local gap impedance at 225 points. The flow conditions cover various flow regimes by controlling the flow rate at the inlet boundary. For each selected inlet and outlet nozzle combination, the water flow rate ranged from 2 to 20 kg/s, and the air flow rate ranged from 2.0 to 20 g/s, which corresponds to 0.4 to 4 m/s and 0.2 to 2.3 m/s of the superficial liquid and gas velocities based on the inlet port area, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.742-752
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• 2017

The bridge type of steel concrete composite rahmen or pre-flex has been applied where a lower depth girder is required due to vertical clearance restrictions caused by the crossing of rivers and roads. On the other hand, because these types are not only complicated to manufacture and construct, but also expensive, void slab bridges may be an alternative. In this study, prefabricated PSC-I shape girder was used to make a void slab and all procedures for bridge development, such as analysis, design, fabrication, and real-scale test, were included in the scope of research. The results of this study will provide sufficient background data to be applied to the field and the structural safety has been verified through experiments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.91-97
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• 2017

The purpose of this study is to get a more precise frequency of hollow core slabs by comparing the observed values from the actual free vibration tests and the predicted values based on the analysis model. The actual free vibration tests were carried out in the construction field using ${\Omega}$ shaped hollow core slabs. Modal analysis is conducted based on the analysis model that takes into account the differences in section properties due to void parts of slab. The differences between the predicted values based on the modal analysis with analysis model and the measured data from the actual tests range from 2~7%. This study demonstrates that the analysis model that incorporates void parts of slab could be used in evaluating serviceability of hollow core slabs with reasonable accuracies.

• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.43-47
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• 1989

In recent years, it has been found that one of the most significant factors in the reduction of the life of concrete pavements is the presence of voids beneath the slab. In the design of pavement, it is assumed that there is a full support through the length of the pavement. When a void develops, this assumption is no longer vaild. With increasing void size, traffic loads have a very a significant increase in stress. Thus, the combination of existing voids and increasing traffic loads results in significant pavement life reduction. Basea on the results of an experimental deflection using Dynaflect device and a theoretical one on the pavement model, this study presents a rational evaluation technique for detecting voids beneath the plain reinforced concrete pavement.

• Magazine of the Korea Concrete Institute
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• v.25 no.2
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• pp.34-38
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• 2013

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