• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.64-64
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• 2021

댐의 중요 구성요소 중 하나인 여수로 구조물은 관행적으로 단위길이당 100m³/s 정도의 유량이 흐를 수 있도록 설계를 하고, 이를 초과할 때는 여수로 구조물에 피해가 가지 않도록 공기혼입 장치를 설치하거나 콘크리트의 설계강도를 증가시키는 대책을 사용하는 것이 일반적이다(댐설계 기준·해설, 2011) 그러나 건설된 지 오래된 댐의 경우 여수로 콘크리트 구조물의 설계강도가 낮고(최저 16.7MPa) 수문방류 횟수가 많아 최근에 건설된 댐 여수로 보다 상대적으로 많은 손상이 발생되어 있어 잦은 보수보강이 요구되고, 점차 유지관리 비용이 증대되고 있어 노후된 여수로 구조물일수록 기능을 유지하면서도 유지관리 비용을 절감할 수 있는 방안의 수립이 요구되고 있다. 이에 본 연구에서는 𐩒𐩒𐩒댐 여수로를 대상으로 2020년 홍수기 전·후의 여수로 바닥슬래브의 손상상태를 3D드론 매핑, 육안조사 및 내구성 조사결과 등을 이용한 정밀분석을 통해 수문방류시 여수로 바닥슬래브에 가장 큰 손상을 일으키는 손상메커니즘으로 유수에 의한 부상(uplift)에 의한 파손 메커니즘(Flow-driven uplift failure mechanism)을 제시하였으며, 여수로 바닥슬래브의 가장 일반적 손상원인으로 간주되고 있는 공동현상(cavitation)이 공동지수(cavitation index)가 0.3이상인 경우에도 발생할 수 있음을 확인하였다. 이와 같은 관찰 및 분석결과는 보다 많은 사례를 통하여 보완될 경우 향후 여수로 구조물의 설계 뿐만 아니라 보수보강 방법이나 유지관리, 더나아가서는 종합적 댐시설물 자산관리 계획을 수립하는데 매우 유용한 자산이 될 수 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.166-175
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• 2009

An experimental study was carried out to estimate the flexural performance of steel fiberreinforced self-compacting concrete. Seven slabs with three different steel fiber-reinforced concretes were prepared to make beam specimens. After proper curing period, each slab was cut to five beams with a diamond saw. The beam specimen was tested with displacement control method to obtain load-deflection curve. As the results, the self-compacting concrete beam showed higher flexural strength, ductility and toughness index compared to the normal concrete beam. This means that steel fiber-reinforced self-compacting concrete can be used more widely in the field of architecture and civil engineering because of its self-compactability and good mechanical properties.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.695-702
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• 2006

The stress distribution and the critical stresses in concrete pavements were analyzed using formulations in the transformed field domains when dual-wheel single-, tandem-, and tridem-axle loads were applied. First the accuracy of the transformed field domain analysis results was verified by comparing with the finite element analysis results. Then, the stress distribution along the longitudinal and transverse directions was investigated, and the effects of slab thickness, concrete elastic modulus, and foundation stiffness on the stress distribution were studied. The effect of the tire contact pressure related to the tire print area was also studied, and the location of the critical stress occurrence in concrete pavements was finally investigated. From this study, it was found that the critical concrete stress due to multi-axle loads became larger as the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The number of axles did not tend to affect the critical stress ratio except for a small foundation stiffness value with which the critical stress ratio became significantly larger as the number of axles increased. The critical stress location in the transverse direction tended to move into the interior as the tire contact pressure increased, the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The critical stress location in the longitudinal direction was under the axle for single- and tandem-axle loads, but for tridem-axle loads, it tended to move under the middle axle from the outer axles as the concrete elastic modulus and/or slab thickness increased and the foundation stiffness decreased.

• Computational Structural Engineering
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• v.4 no.4
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• pp.79-89
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• 1991

New design method of R/C slab system based on finite element method has been presented. The proposed method can substitute inaccurate existing method, which has limitation in its application, and provide accurate and efficient design results for any type of slab system. Isoparametric plate element used in the slab design has been efficiently formulated to save computational time. Reinforcement has been determined by strength design method and compared with code minimum values. Graphical output through comprehensive contour map for resulting moments and designed steel areas has considerably facilitated design process. Accurate shear results from isoparametric plate element enabled to check punching shear in a proper manner. In addition to strength design criteria, serviceability has also been checked by utilizing newly developed inelastic deflection multiplier method. An example for circular slab with opening showed that the proposed method could be applied to design of irregular slab without any difficulty.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.75-82
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• 2019

Slab panels are very important to develop asphalt concrete (AC) track for minimizing the roadbed stress due to the train load and reducing the plastic deformation of infrared-sensitive AC. In this study, the slab panel for AC track was developed through the shape design and the indoor performance test and its structural integrity has been investigated through the finite element analysis under the flexural tensile stress and the design moment according to various static load combination by KRL-2012 standard train load model and KR-C code. In order to verify the suitability of the slab panel for AC track, static bending strength test and dynamic bending strength test were performed according to EN 13230-2. Results show that the slab panel for AC track satisfies all the performance standards required by European standards such as crack loads and crack extension.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.63-72
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• 1998

This study is to develop a technique for micro-vibration analysis and control of concrete slabs to fulfil the vibration criteria for working environments. The proposed technique is for determining the unknown forces from accelerance of two concerned points and the micro-vibration analysis and control of concrete slabs are then validated by numerical model and structural tests. And it is recommended that the natural frequency of structures for micro-vibration control design should be above 25 Hz~30 Hz, and 1.5 times forcing frequency in case of 3~5% structural damping ratio of concrete structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.305-308
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• 2008

This paper presents the results of an experimental study carried out Prestressed Concrete Slab System of WAffle Shape(WAS), was perfomed in order to inverstigate it connection shear behavior according to primary paramaters: connection interval, filling matarial. Specimen is produced in Precast Concrete factories and it comprised one WAS panel and two half WAS panels and then it is filled with packing. Within the ranges of the parameters of the connection details used in this test, connections can develop greater shear strength than the nominal shear strength and the design service load for parking structures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1303-1313
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• 2013

In this study, the reference values for the internal forces of the rail supports caused by a wheel load, a unit vertical displacement, a unit end rotation in examination of the serviceability of concrete slab track bridge were obtained. In analysis, the analysis models of which the rail was continuously and discretely supported by elastic springs were used. The internal forces of the rail supports from the analysis were compared with the results provided in the DS 804 regulations and agreed with well. In addition, the effects of the space between the rail supports and the stiffness of fastener on the internal forces of the rail supports were investigated.

• Journal of the Korean GEO-environmental Society
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• v.20 no.4
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• pp.31-38
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• 2019

Field tests with carbon fiber heating wire (CFHW) embedded inside concrete slab were performed to present the alternative heating material capable of avoid the adverse effects of traditional de-freezing salt on the structures and environment. The CFHW was inserted into the concrete slab in the shape of 'ㄷ' to improve the heat superposition and the temperature on the surface was measured using iButton. The results showed that the temperature where the CFHW's were faced with each other increased to above zero after 12-hour at outdoor air temperature of $-6^{\circ}C$. Comparatively, the temperature slightly increased where the CFHW was embedded on one side because the heat was not superimposed. Hence, it can be said that the CFHW is a suitable heating material to prevent the concrete road from being frozen.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.567-575
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• 2012

A research was conducted to develop a 2-D nonlinear Galerkin finite element analysis of reinforced concrete structures subjected to high temperature with experiments. Algorithms for calculating the closed-form element stiffness for a triangular element with a fully populated material conductance are developed. The validity of the numerical model used in the program is established by comparing the prediction from the computer program with results from full-scale fire resistance tests. Details of fire resistance experiments carried out on reinforced concrete slabs, together with results, are presented. The results obtained from experimental test indicated in that the proposed numerical model and the implemented codes are accurate and reliable. The changes in thermal parameters are discussed from the point of view of changes of structure and chemical composition due to the high temperature exposure. The proposed numerical model takes into account time-varying thermal loads, convection and radiation affected heat fluctuation, and temperature-dependent material properties. Although, this study considered standard fire scenario for reinforced concrete slabs, other time versus temperature relationship can be easily incorporated.