• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.406-409
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• 2006

Serviceability resign is required to control the cracking at the joint of precast decks having longitudinal prestress in continuous composite bridges. Especially, details of twin girder bridges are complex not only due to main reinforcements and transverse prestress for the resign of long-span concrete slabs but also due to shear pockets for obtaining the composite action. This paper suggests the design guidelines for the magnitude of the effective prestress and for the selection of filling materials and their requirements in order to use precast decks for twin-girder continuous composite bridges. The necessary initial prestress was also evaluated through the long-term behavior analysis. From the analysis, existing design examples were revised and their effectiveness was estimated. When a filling material having bonding strength higher than the requirement is used in the region of high negative moment, uniform configuration of longitudinal prestressing steels along the whole span length of continuous composite bridges can be achieved resulting in simplification of details and enhancement of the construction costs.

• Computers and Concrete
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• 제2권2호
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• pp.147-164
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• 2005

This paper summarizes an experimental study on the seismic behavior of lower stories of a mid-rise reinforced concrete frame building. Two reinforced concrete frames with two stories and one span were tested and each frame represents lower two stories of an 11-story RC frame building. Both frames were designed in accordance with Japanese design guidelines and were identical except in the variation of axial force. The tests demonstrated that the overall load-displacement relations of the two frames were nearly the same and the first-story column shear was closely related to the column axial load. The columns and beams elongated during both of the tests, with the second-floor beam elongation exceeding 1.5% of the beam clear span length. The frame with higher axial loads developed more cracks that the frame under moderate axial load.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.73-84
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• 2016

This study analyzes the four composition elements : profile, anchorage and connection, material and member rigidity, stability, as the main composition design elements of flexure structure systems, in order to explore possibilities for more various structure designs in architectures with flexure structure system. It also examines typical design methods that use the mentioned four composition elements. At the results, this research presents an understanding of the differences between funicular shape and non-funicular shape and mechanical features of the shapes in the profile element, regarding to the ratio of rise height to span length(f/l). Also, the typical design methods are presented for the designable usages of the hinge joints and the fix joints, and for the applications of member rigidity expressed by the index of the ratio of member depth to span length(d/l). And it was presented that connection styles, addition of brace members, placement of shear walls are the main design methods in the stability element. This data would be useful to architectural designs concerning integrated design with structures.

• Nuclear Engineering and Technology
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• 제40권1호
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• pp.37-48
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• 2008

Flow fields inside feeder pipes have been simulated numerically using a CFD (computational fluid dynamics) code to calculate the shear stress distribution, which is the most important factor in predicting the local regions of feeder pipes highly susceptible to FAC (flow-accelerated corrosion)-induced wall thinning. The CFD approach, with schemes used in this study, to simulate the flow situations inside the CANDU feeder pipes has been verified as it showed a good agreement between the investigation results for the failed feedwater pipe at Surry unit 2 plant in the U.S. and the CFD calculation. Sensitivity studies of the three geometrical parameters, such as angle of the first and second bends, length of the first span between the grayloc hub and the first bend, and length of the second span between the first and the second bends have been performed. CFD analysis reveals that the local regions of feeder pipes of Wolsung unit 1 in Korea, on which wall thickness measurements have been performed so far, are not coincident with the worst regions predicted by the present CFD analysis located in the connection region of straight and bend pipe near the inlet part of the bend intrados. Finally, based on the results of the present CFD analysis, a guide to the selection of the weakest local positions where the measurement of wall thickness should be performed with higher priority has been provided.

• 콘크리트학회논문집
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• 제22권5호
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• pp.703-710
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• 2010

기존 구조물에서 RC보는 여러 가지 이유로 불충분한 전단에 대한 문제에 직면하게 된다. 전단내력이 부족한 RC보의 전단 보강방법으로 강판이 널리 사용되고 있다. 본 연구에서는 앵커볼트가 체결된 경사, 수직 슬릿형 강판의 표면부착에 의해 전단보강된 RC보에 대한 실험을 하였으며, 여러 형태의 앵커볼트 체결 슬릿형 강판으로 보강된 RC보에 대한 전단보강효과, 파괴모드 및 전단내력을 평가하는 것을 연구의 목적으로 하였다. 실험의 변수는 앵커볼트가 부착된 슬릿의 폭, 간격, 경사각 및 수직 길이로 하였다. 연구 결과, 에폭시 부착과 볼트 체결로 보강된 슬릿형 강판 실험체의 파괴 유형은 최대하중 시 전단파괴 모드로 나타났다. 휨균열은 보의 인장측에서 최초로 발생하였으며, 경사 균열은 전단스팬에서 발생하였다. 최종적으로 에폭시 부착과 볼트 체결로 보강된 슬릿형 강판에서의 급격한 박리현상은 지연되었으며, RC보의 본체로부터 완전하게 분리 되지는 않음을 알 수 있었다.

• Steel and Composite Structures
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• 제48권6호
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• pp.693-708
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• 2023

Composite beams, two materials joined together, have become more common in structural engineering over the past few decades because they have better mechanical and structural properties. The shear connectors between their layers exhibit some deformability with finite stiffness, resulting in interfacial shear slip, a phenomenon known as partial shear interaction. Such a partial shear interaction contributes significantly to the composite beams. To provide precise predictions of the geometric nonlinear behavior shown by two-layered composite beams with interfacial shear slips, a robust analytical model has been developed that incorporates the influence of significant displacements. The application of a higher-order beam theory to the two material layers results in a third-order adjustment of the longitudinal displacement within each layer along the depth of the beam. Deformable shear connectors are employed at the interface to represent the partial shear interaction by means of a sequence of shear connectors that are evenly distributed throughout the beam's length. The Von-Karman theory of large deflection incorporates geometric nonlinearity into the governing equations, which are then solved analytically using the Navier solution technique. Suggested model exhibits a notable level of agreement with published findings, and numerical outputs derived from finite element (FE) model. Large displacement substantially reduces deflection, interfacial shear slip, and stress values. Geometric nonlinearity has a significant impact on beams with larger span-to-depth ratio and a greater degree of shear connector deformability. Potentially, the analytical model can accurately predict the geometric nonlinear responses of composite beams. The model has a high degree of generality, which might aid in the numerical solution of composite beams with varying configurations and shear criteria.

• Computers and Concrete
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• 제14권6호
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• pp.745-765
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• 2014

In this paper, it is aimed to determine the finite element model updating effects on the structural behavior of long span concrete highway bridges. Birecik Highway Bridge located on the 81stkm of Sanliurfa-Gaziantep state highway over Firat River in Turkey is selected as a case study. The bridge consist of fourteen spans, each of span has a nearly 26m. The total bridge length is 380m and width of bridge is 10m. Firstly, the analytical dynamic characteristics such as natural frequencies and mode shapes are attained from finite element analyses using SAP2000 program. After, experimental dynamic characteristics are specified from field investigations using Operational Modal Analysis method. Enhanced Frequency Domain Decomposition method in the frequency domain is used to extract the dynamic characteristics such as natural frequencies, mode shapes and damping ratios. Analytically and experimentally identified dynamic characteristics are compared with each other and finite element model of the bridge is updated to reduce the differences by changing of some uncertain parameters such as section properties, damages, boundary conditions and material properties. At the end of the study, structural performance of the highway bridge is determined under dead load, live load, and dynamic loads before and after model updating to specify the updating effect. Displacements, internal forces and stresses are used as comparison parameters. From the study, it is seen that the ambient vibration measurements are enough to identify the most significant modes of long span highway bridges. Maximum differences between the natural frequencies are reduced averagely from %46.7 to %2.39 by model updating. A good harmony is found between mode shapes after finite element model updating. It is demonstrated that finite element model updating has an important effect on the structural performance of the arch type long span highway bridge. Maximum displacements, shear forces, bending moments and compressive stresses are reduced %28.6, %21.0, %19.22, and %33.3-20.0, respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.340-343
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• 2007

The differential equations governing free, in-plane vibrations of non-circular arches with the translational (radial and tangential directions) and rotational springs at the ends, including the effects of rotatory inertia, shear deformation and axial deformation, are solved numerically using the corresponding boundary conditions. The lowest four natural frequencies for the parabolic geometry are calculated over a range of non-dimensional system parameters: the arch rise to span length ratio, the slenderness ratio, and the translational and rotational spring parameters.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1097-1102
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• 2001

Seismic safety of continuous span concrete bridge can be enhanced by distributing a large seismic lateral load to each supporting pier. A new viscoelastic device called Shock Transmission Unit(STU), which is a simple cylinder-piston assembly packed with a so-called silicone putty compound, enables the lateral seismic load to be transmitted to the pier by installation of the device to movable bearings of the bridge. The seismic safety of concrete bridges having the STU depends on not only safety of the bridges globally but also safety of anchor systems which anchors the STU to concrete pier. An experimental investigation is performed to study the behavior of cast-in-place anchor and post-installed anchor subjected to shear load statically and cyclically according to different edge distance, embedment length, and anchor spacing. Finally, the experimental results are compared with results by design methods of ACI and CCD, and results by FEM analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.706-711
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• 2000

This paper deals with the free vibrations of horizontally curved beams on an elastic foundation. Taking into account the effects of rotatory inertia and shear deformation, the differential equations governing free vibrations of noncircular curved beams resting on Pasternak-type foundations are derived and solved numerically. The lowest three natural frequencies for parabolic curved beams with hinged-hinged and clamped-clamped end restraints are calculated. Numerical results are presented to show the effects on the natural frequencies of the non-dimensional system parameters: the horizontal rise to span length ratio, the Winkler foundation parameter, the shear foundation parameter, and the width ratio of contact area between the beam and foundation.