• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.527-533
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• 2013

This paper presents damage detection and estimation of stiffness parameter on a concrete scale model and a real structure of concrete pontoon using dynamic properties such as mode shapes and natural frequencies. In case of damage detection, dynamic impact test on a concrete scale model is accomplished to extract mode shapes and the practicality is verified by utilizing a damage detection technique. And the stiffness parameter of a real structure of concrete pontoon was estimated via system identification technique using the natural frequencies of the structure. The results indicate that the damaged elements of the scale model are found exactly using damage detection technique and the effective stiffness property of the real structure of concrete pontoon can be estimated by system identification technique.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.641-650
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• 2009

This paper presents new equations for member forces in concrete floating structures under wave loadings. The currently adopted design equations for wave loadings disregard the effect of mismatch between design wave length and the length of the structure. In most cases, however, additional internal forces occur due to disequilibriating buoyancy caused by the difference between design wave length and the length of the structure. In this study, new design equations considering the influence of the disequlibriating buoyancy is proposed. In addition, finite element solutions are sought to demonstrate the adequacy of the proposed design formulae in estimating the actual internal forces considering the structure as either rigid or flexible. It has been found that member forces are decreased approximately to around 55% for flexible model when compared with the rigid one.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.285-287
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• 2012

염해는 철근 콘크리트 구조물의 주요 열화원인으로서 특히 수해양 부유식 건축물의 상부구조는 비래염분에 의한 피해에 노출되어 있고, 해수에 접하고 있는 함체는 다공질 콘크리트의 모세관으로 염수이온이 침투하므로 상당히 높은 수위의 열화 환경에 노출되어 있다고 분류할 수 있다. 본 연구는 해양에서 유입되는 비래염분량을 정량화하여 철근 콘크리트 구조물 뿐만아니라 강재 건자재의 장수명화를 꾀하는 기초자료를 구축하고자 하였다. 1년간에 걸쳐 측정된 비래염분유입 지역은 기존연구에서 조사된 1km 범위을 상당히 초과하고 있으며 그 량도 강재 발청농도를 탁월하게 상회하는 것으로 분석되었다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.319-322
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• 2009

콘크리트 부유구조물에서 파랑하중의 영향에 의하여 발생하는 부재내력 산정식을 제시하였다. 기존의 설계식은 구조물의 길이와 파장 길이가 일치할 때에 적용이 가능하다. 그러나 대부분의 경우 구조물의 길이와 파장 길이가 일치하지 않기 때문에 비평형 부력에 의한 추가적인 모멘트가 발생한다. 따라서 본 연구에서는 부유구조물을 강체로 가정하고 비평형 부력의 영향을 고려한 설계식을 제시하였고 이를 유한요소해석에 의한 결과와 비교하여 그 타당성을 보여주었다.

• Journal of Navigation and Port Research
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• v.36 no.3
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• pp.197-204
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• 2012

The behavior of floating structures constructed with precast concrete modules is dependent of the behavior of joints between the concrete modules. To accurately predict the floating structure response under the ultimate loading, knowledge of joint behavior is essential. This study aims to investigate the structural behavior of concrete module joints under various configuration of joint and confining stress levels. The shear behavior, shear capacity and crack patterns of shear keys in concrete module have been studied. Test results indicated that the shear capacity of joints increased as shear key inclination increased. In addition, shear capacity of concrete module joint increased with the increase of confining stress levels. The test results were compared with the AASHTO design recommendations. The AASHTO design recommendations underestimated the shear strength of test specimens.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.155-163
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• 2013

This study explores the structural behavior of module joints in floating concrete structures subjected to shear. Crack patterns, shear behavior and shear capacity of shear keys in joints of concrete module were investigated. Test parameters included shear key shape, or inclination of shear keys, confining stress levels and compressive strength of concrete. Test results showed that shear strength of joints increased as shear key inclination increased. Test results also showed that shear strength of concrete module joints increased with the increase of confining stress levels. The equation for predicting shear strength of joints was suggested, which was based on the test results. Shear strength prediction by using the equation suggested in this study showed good agreement with test results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5B
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• pp.313-320
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• 2012

A hybrid floating structure system combined with pontoon and semi-submersible type modules is proposed. This new system can reduce tensile forces of bottom slabs which could cause fatal damage of concrete floating structures. We performed a parametric study on the dimensions of this new system and investigate the sensitivity of the parameters to the behavior. In order to investigate various cases efficiently, we developed a simple two-step static analysis method for the fluid-structure interaction. An optimum system is derived from the investigation of the analysis results, weights and drafts of the hybrid structure. This study shows that introducing this new system to concrete floating structures is an effective way to reduce the tensile force of the bottm slab of such a floating structure. Also, it was found that when the length of the semi-submersible module is about 15%, the behavior would be optimal in the considered case.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.72-80
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• 2015

In this study, comparative analysis has been performed with regard to a bending stress and deformation at bottom slab of a concrete floating container terminal by live load distributions. In addition, a structural performance and behavior of the floating structure is considered using a numerical analysis. Through reviewed structural performance of a floating structure by live load distribution, the structure presented tensile behavior by two live load cases (A, B, D-type). Then, the other live load cases (C, E, F, G, H, I, J-type) shows compressive behavior. Especially, immoderately compressive stress was generated on bottom slab at specific load distribution. but, that should be decreased through controling buoyancy pre-flexion. Through reviewed structural behavior, slopes of structure by four live load cases (B, E, F, H-type) were exceeded in design criteria of mega-float. It should be estimated that it get out of the load case at loading container. In all, the present study can be considered as a benchmark of a floating container terminal in the absence of analysis and will be used to guide-line about serviceability of concrete floating container terminal.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.315-325
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• 2017

This study aims to provide information for the design and use of structural lightweight concrete (SLWC) for floating concrete structures in a marine environment. An experimental program was set up and comprehensive experimental campaign were carried out to determine SLWC mix proportions that can satisfy specified concrete strength, density, and slump values all of them were determined from previous research. Comparisons with previous SLWC mix designs that have been utilized for actual floating concrete structures were made. Key aspects needed to be considered regarding to the use of SLWC for floating marine concrete structures were discussed.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.648-656
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• 2019

The ecological changes in the ocean due to the drastic global warming require that action be taken to sustain the productivity of fisheries. Proper ocean facilities could help prevent the loss of the expenditures made on marine aquaculture and reduce the related compensation for various ocean conditions. The aim of this study was to develop a floating ocean wave-breaker using an eco-friendly concrete and conducting a site survey, a structural analysis, and a test of towing the tank. As a result, the wave at the fish farm would be reduced. The results of the holding power of anchors and the capability of moving the floating structures were considered in the design of the wave-breaker. The analyses of the material properties of concrete and the steel structures, as well as the CAPEX and OPEX analyses of the manufacturing and operation processes confirmed the superiority of the floating concrete wave-breaker. In particular, this study demonstrated that the concrete floating breakwater can protect the fish farm against typhoons and reverse-waves, thereby reducing losses of the fish.