• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.970-975
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• 2005

측면웨어(side weir)는 본류의 수위가 한계수위 이상으로 상승할 경우 본류로부터 저류지나 분수로(distributary channel)로 흐름을 전환하기 위하여 사용하는 수공구조물이다. 최근 들어 치수와 관련된 계획에서 본류의 홍수량 중 일부를 저류지나 홍수 우회수로로 전환시키는 시설에 대한 관심이 높아지고 있다. 측면웨어가 하천에 설치되는 경우, 측면웨어 부근 표층부의 흐름은 측면웨어의 영향을 크게 받으며, 수의바닥이나 측면웨어에서 떨어진 지점의 흐름은 측면웨어의 영향을 작게 받는 등 측면웨어 주변부는 3차원적인 흐름특성을 보인다. 또한 측면웨어를 월류하는 흐름이 일반 웨어와 같이 웨어 마루부에 대하여 직각방향으로 흐르지 않고 본류의 유속에 따라 비스듬하게 흐르게 된다. 이러한 흐름특성으로 인해 측면웨어를 통과하는 유량은 본류의 하폭, 본류의 흐름특성, 측면웨어의 길이 및 설치위치 등에 따라 각기 다르게 산정되는 것으로 알려져 있다. 본 연구에서는 기존 측면웨에에 관한 연구를 정리하고 상용 프로그램인 FLOW-3D를 이용하여 측면웨어가 설치된 경우의 흐름을 해석하였다. 해석결과는 기존 실험연구에 바탕을 둔 이론식과 비교하였다. 계산격자는 구조물 부근의 흐름이 급변하는 곳은 격자크기를 작게, 흐름의 변화가 완만한 곳은 격자크기를 크게 하였다. 경계조건으로 상류는 유량, 하류는 수위경계를 입력하였다. 본 수치모의결과와 이론식을 이용하여 산정한 월류량을 비교한 결과 약 $10-30\% 내외의 오차가 발생하는 것으로 나타났다. 본류의 흐름은 웨어의 길이가 짧을수록 상$\cdot$하류단의 수위차가 작아지며 유속의 경우 웨어길이가 길고, 높이가 낮을수록 빨라진다. 측면웨어 주변부 흐름의 경우, 웨어의 길이가 짧을수록 방류강도가 강하고 횡방향의 수면변위가 급하게 형성되고 있음을 알 수 있다 또한, 웨어의 길이가 상대적으로 길어질 경우에는 3차원적 흐름특성에 의하여 유속의 분포가 다양하여 이론식과 결과의 오차가 점점 더 커짐을 알 수 있다. 본 연구는 사각형수로에 측면웨어가 설치된 경우, 월류량과 수리학적 거동을 해석할 때 수치모형실험이 수리모형실험과 더불어 유용한 해석도구로 이용될 수 있음을 보인 깃으로 이후 관련 구조물의 설계와 해석 시 참고자료로 이용 가능할 것으로 판단된다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.421-428
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• 2009

In this study, an equivalent plate element model has been developed for an efficient vibration analysis of a biaxial hollow slab. To this end, equivalent mass and stiffness of equivalent plate element models corresponding to solid element models of example biaxial hollow slabs were calculated. To verify the efficiency and accuracy of the equivalent plate element models, structural analyses of example structures were performed. Analytical results showed that the natural frequencies of the equivalent plate element models were very close to those of the solid element models. Time history analyses of example biaxial hollow slabs subjected to walking load were conducted using the equivalent plate element models and the solid element models, and the results were compared. It could be seen based on the analytical results that the equivalent plate element model could provide very accurate results compared to the solid element model with significantly reduced analysis time.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.6
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• pp.463-470
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• 2013

In this paper, 2D simple analyses were performed in order to predict the large torsional oscillations in a suspension bridge based on Makenna and Tuama model(2001). The existing model(Makenna and Tuama, 2001) has shown unrealistic results as the wind speed increases and frequency decreases. Furthermore, resonance could not be simulated by the existing model. Therefore, in this study, new model was proposed with a consideration of the torsional resistance. The vertical and rotational behaviors of the deck in the suspension bridge were analyzed. Analysis results showed that at first vertical oscillations were observed and it was gradually transformed to the rotation oscillations. With the consideration of the torsional resistance, it was shown that vertical behavior were stabilized as time passed. However, the rotational behavior was not stabilized and was kept until the end of analysis. Beat periods decreased while the wind speed increased. The resonance of the rotational mode was dependent to the rotational resistance. Obtained results could be applied for the design of the suspension bridge under the wind load.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.55-61
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• 2017

Recently several researches have been conducted to develop sliding track system in which friction between concrete track and bridge slab has been reduced. This paper investigated shear load carrying capacity of lateral supporting concrete block which should be implemented to resist lateral load due to train in sliding track system. In order to evaluate shear load carrying capacity of lateral supporting concrete block, analytical model has been developed considering concrete friction and rebar dowel action along construction joint. The proposed model predicted test results on the shear load carrying capacity from literature conservatively by 13~23% because effect of aggregate interlock along crack surface was neglected. Since construction joint status is ambiguous on construction site, it can be concluded that the proposed model can be used for reasonable design of lateral supporting concrete block. Based on the proposed model, design proposal for lateral supporting concrete block has been established.

• Geotechnical Engineering
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• v.12 no.5
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• pp.27-40
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• 1996

Box culvert has long since been used for various purposes , water and sewerage works, communication and electricity facilities, subway, railway, etc. In urban area, the construetion of box culvert generally consists of excavation-installation of the culvert-backfill. However, the existing design methods for earth pressure on the box culvert do not take into account the excavation(or backfill) geometry. ' A new method considering excavation geometry for earth pressure on box culvert is suggested here. The lateral earth pressures by the newly suggested method agree relatively with results of finite element analyses, but those of existing method are greatly overestimated. The vertical pressure on the top of the box culvert by the new method is similar to those of existing method and finite element analysis. However, the reactional pressure on the bottom of the box culvert depends largely upon the stiffness of the foundation soil. The reactional pressure by the new method agrees well with that of finite element analysis, only when the stiffness is low. From the finite element analysis it is shown that the lateral earth pressure on box culvert depends upon the excavated slope (G) and the net bottom distance (Bc).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.6
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• pp.465-473
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• 2008

Type II compressed natural gas(CNG) storage vessels for automobiles have been acknowledged for their excellence and have recently become established in local regions. Their supply is not only to automakers in Korea such as Hyundai Motors but they are being increasingly exported. Although the available products have undergone safety evaluations and are certified by an authorized institution they are still short of the optimal design that is possible for such storage vessels. This research investigates the shape and thickness of the dome with the aim of optimizing the type II CNG storage vessels by using a finite element analysis technique. CNG storage vessels can be largely divided into 3 parts namely, the hear part, the cylinder part and the dome part. The head part is designed by means of a hot spinning process and this method is safer than that used in the design of the dome part even though its shape is similar. The thickness of the liners and reinforcing materials was optimized based on the requirements of the cylinder and dome parts. In addition, the shape of the dome, which is most suitable for Type II CNG storage vessels, is proposed by a process of review and analysis of various existing shape, and then conducting a structural stability evaluation to ensure the optimal design plan.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.147-147
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• 2011

이상기후 및 극한 홍수 발생빈도의 증가 등으로 인해 많은 수공 구조물이 붕괴 위험에 노출되어 있다. 사전 피해 예방 및 경감을 위해 다양한 수공구조물의 붕괴 현상에 대하여 수리실험적 접근방법을 통한 현상이해 및 예상결과 비교 검증이 필요하다. 그 중에서 제방붕괴에 대한 수리실험은 수치모의를 통한 분석의 어려움 때문에 대부분 모형실험을 통해서 이루어지고 있는 실정이다. 본 연구에서는 실제규모의 제방붕괴 선행실험의 측정결과를 활용하여 실험설계에 이용 하였다. 모형은 실험공간의 규모를 고려하여 축척을 1:10 으로하고, 하도내 흐름 안정을 위해 수로의 길이 는 16, 저폭은 $b\geq10h$를 만족하는 하천으로 설계하여 b를 3m로 설정 하였다. Fr수는 0.29로 원형과 동일하게 하고, 그에 따른 유량 ( )는 0.538m/s로 하였다. 실제 모형 제작에서는 현장 실험실의 펌프용량에 따른 가용유량 ($Q__{max}$)의 제약에 따라 수로가 직선이고 좌우가 대칭인 점을 감안하여 폭을 1/2로 절단 하고 유량은 $0.269m^3/s$(Q/2)를 공급하였다. 위와 같이 모형제작을 위한 실험 설계시 현장 여건을 고려하여 모형을 변형할 경우 EIM(Experimental Information Modeling)을 이용한 수리영향에 대한 분석을 통한 설계검증이 필요하다. FLOW-3D를 이용한 3차원 수치모의를 통하여 동일 지점에서의 유속과 수심을 분석하여 흐름양상을 비교 하였으며, 유속과 수심의 측정위치는 그림 1에 도시하였다. 수치모의 결과 측정지점에서의 수위가 하도 바닥을 기준으로 0.25m로 동일할 경우 수로 단면에 대한 유속 분포가 제방을 기준으로 2b/3까지는 유사한 경향을 보였다. 그 결과, $b\geq10h$인 수로에서 제방붕괴를 위한 모형 설계시 하도 폭을 1/2만 만들 경우에도 실험의 신뢰성이 확보된다는 것을 확인하였다.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.589-600
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• 1997

Cold-formed deck sections are used in many composite floor slab applications wherein the steel deck serves not only as the form for the concrete during construction but also as the principal tensile reinforcement for the bottom fiber of the composite slab. This paper provides the results of an experimental study performed for the composite slabs with the new shaped deck plates with the locking ribs, the dove tails, and the powerful embossment, which are the mechanical means to improve positive interlocking effect between the deck and the concrete. A total of 28 specimens are tested to investigate the composite effects between the concrete and metal deck plate. Important parameters in this are the span length, the thickness of the deck plate, support condition, and whether shear studs are placed at each support or not. The test results are summarized for the maximum load and failure behavior for the specimens.

• Journal of Korean Society of Steel Construction
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• v.21 no.1
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• pp.93-103
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• 2009

Two-girder bridge is composed of primary members such as deck slab and main girder, and secondary member such as cross beam, vertical and horizontal stiffeners etc,. Two-girder bridge is prescribed as a non-redundant load path structure in the ASSHTO and the Korean Highway Bridge Design Code. Such structure is that if one girder is damaged, problems of function and safety of the bridge are caused. From the reasons, fatigue cracks in two-girder bridge can affect safety of the bridge seriously. Therefore, in this paper, fatigue evaluation was performed at connection parts of vertical stiffener and web with radius of curvature of scallop of vertical stiffener and thickness of web as variables. Such joint is known as a detail which has high possibility of fatigue crack in the bridge. Based upon the analytical results, preferable joint detail in terms of fatigue and simple empirical formula for fatigue evaluation of the detail were suggested.

• Journal of the Society of Disaster Information
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• v.13 no.2
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• pp.249-257
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• 2017

Recently, a cable disconnection accident occurred due to a lightning strike at the Seohae Bridge located in Dangjin-Pyeongtaek City. This is a natural occurrence, but it is a recall that it is very important to review the safety issues due to the disconnection of cable bridges. In other words, the role of cables in cable bridges has a profound effect on the safety of the structure, and it has become necessary to grasp the effect on the entire structural system. The cable bridge is an economic bridge that builds the main tower and supports the bottom plate by cable. The influence of the cable is the main member, which is a big influence on the safety of the whole bridge system. In the cable-stayed bridge, the cables exhibit nonlinear behavior because of the change in sag, due to the dead weight of the cable, which occurs with changing tension in the cable resulting from the movement of the end points of the cable as the bridge is loaded. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.