• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1747-1752
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• 2008

강원도 산간지역에 위치한 소하천의 경우 유송잡물 및 토석류에 의하여 교량이 파괴되거나, 통수능이 작아져 댐의 역할을 하게 됨으로 인해 교량 상류지역이 침수피해를 입는 경우가 많이 발생하고 있으며 강원도 산간지역에 설치된 소규모 수공구조물들은 교량의 경우 교각이 많아 경간장이 짧고, 교량 상판이 제방고 보다 낮게 설치되어 있는 등 하천흐름에 장애를 주는 많은 요인들을 내재하고 있어 홍수시 하천유량의 증가에 따른 하천흐름 해석, 유송잡물의 발생원인 및 수공구조물에 미치는 영향들에 관한 판단기준 마련이 시급한 실정이다. 유송잡물의 발생경로는 대부분 산지계류에서 집중호우시 산사태발생에 따른 유목과 토석류 발생이 주원인이 된다. 또한 유송잡물은 큰 홍수시 고수위가 오랜 시간동안 지속될 경우 가장 많이 발생하는데 이때 발생한 유송잡물은 개별적으로 이송되고 일반적으로 하천의 중앙으로 이동하는 경향이 있으며 수심이 깊고 유속이 빠른 곳에 집중된다. 또한 유송잡물은 큰 홍수시 고수위가 오랜 시간동안 지속될 경우 가장 많이 발생하는데 이때 발생한 유송잡물은 개별적으로 이송되고 일반적으로 하천의 중앙으로 이동하는 경향이 있으며 수심이 깊고 유속이 빠른 곳에 집중된다. 본 연구에서는 홍수시 유송잡물 이동특성에 대한 국내 외 문헌조사, 현장피해사례조사 및 현장모니터링 조사를 실시하고 1차원 모형인 HEC-RAS와 2차원 모형인 RMA-2를 이용하여 수리모델링 분석에 따른 수치모의를 실시하고 분석하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.100-109
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• 2011

Recently, the concrete-steel hybrid extradosed bridge has been proposed as alternative bridge type at long span site. The hybrid extradosed bridge adopts light orthogonal deck girder instead of heavy concrete deck girder at the center span of bridge, and it enables to construct long-span bridge. And also, for this bridge type the decrease of self-weight of girder enables to reduce girder depth and side span length of extradosed bridge, so its type has more efficient structural behavior and makes it possible to perform optimal bridge design. Therefore, it is very important to set up the procedure and parameters of optimal design for concrete-steel hybrid extradosed bridge. In this study, the effects of design parameters (the variation of pylon height, bridge deck depth and orthogonal deck girder length) are discussed. And numerical analysis and sensitivity analysis are carried out according to these parameters. And design weight values about these parameters are quantitatively suggested to reflect characteristics of concrete-steel hybrid bridge.

• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.317-322
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• 2002

In this study, structural optimum design was applied to the girder of magnet over head crane. The optimization was carried out using ANSYS Code for the deadweight of girder, especially focused on the thickness of its upper, lower, side and reinforced plates. The weight could be reduced up to around 15% with constraints of its deformation, stress, natural frequency and buckling strength. The structural safety was also verified by the buckling analysis of its panel structure. It might be thought to be very useful to design the conventional structures for the weight save through the structural optimization. Also this paper grasped the sensitivity influenced the design variables upon the objective function and the state variables.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.14-19
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• 2010

Theories for advanced composite structures are too difficult for such design engineers for construction and some simple but accurate enough methods are necessary. The senior author has reported that some laminate orientations have decreasing values of $D_{16}$, $B_{16}$, $D_{26}$ and $B_{26}$ stiffnesses as the ply number increases. For such plates, the fiber orientations given above behave as specially orthotropic plates and simple formulas developed by the senior author. Most of the bridge and building slabs on girders have large aspect ratios. For such cases further simplification is possible by neglecting the effect of the longitudinal moment terms(Mx) on the relevant partial differential equations of equilibrium. In this paper. the influence of the aspect ratio on the natural frequency of the composite laminated plates is studied and it is concluded that the method used is sufficiently accurate for engineering purposes.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.133-136
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• 2008

The cost of repairing the deterioration of concrete structures due to corrosion of the reinforcement steel has been the prominent figure in the maintenacne of the reinforced-concrete infrastructures. As an alternative material to steel reinforcement, the use of Glass Fiber Reinforced Polymer (GFRP) bar in concrete is being actively studied for the high resistance of chemical environment and high strength to weight ratio properties of GFRP. However, there remain various aspects of GFRP properties that still need to be studied before the standard design criteria can be established. One of the imminent issues is the bond between GFRP and concrete. In this study, the bond-behavior of GFRP bars in concrete is investigated via the pullout test with varying parameters: surface condition of GFRP bars and concrete compression strength. And the local bond-stress model of GFRP rabars with applying monotonc load was also derived from the present test.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.101-104
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• 2008

The cost of repairing the deterioration of concrete structures due to corrosion of the reinforcement steel has been the prominent figure in the maintenacne of the reinforced-concrete infrastructures. As an alternative material to steel reinforcement, the use of Fiber Reinforced Polymer (FRP) bar in concrete is being actively studied for the high resistance of chemical environment and high strength to weight ratio properties of FRP. However, there remain various aspects of FRP properties that still need to be studied before the standard design criteria can be established. One of the imminent issues is the bond between FRP and concrete. In this study, the bond-behavior of FRP bars in concrete is investigated via the pullout test with three varying parameters: surface condition of FRP bars, concrete compression strength, and cyclic loading patterns. As a result of experiment, the bond strength of GFRP increased with the concrete compression strength increasing and decreased with applying cyclic load.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.77-87
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• 2013

A present LSD (limited state design) code for temperature load in the domestic bridge design has applied a uniform standard for various bridge types. In this study, in order to calculate the effective temperature, a specimen of steel box girder bridge section with real size dimension was manufactured. For a year, the temperature data were measured at the 18 point in steel deck of steel box girder bridges specimen. Effective temperature within the cross section according to atmospheric temperature was calculated by this experiment data. The analyzed results were very similar correlation when compared with the effective temperature of the Euro Code. Therefore, the effective temperature which calculated based on the present data could be used as the basic data in order to present to the appropriate design criteria for the thermal loads on the domestic bridge design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.99-106
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• 2014

In order to study the reasonable design thermal loads, the steel box girder bridge specimen which have no concrete slab was manufactured with the real size dimension. The temperature data were measured for 5 month at the 18 thermo gauges which were attached according to height. The temperature differences between the top and bottom flange in steel box girder specimen were calculated and the temperature gradient models were proposed by the probabilistic method. This proposed model showed a correlation of approximately 97% when compared with the similar model of Euro Code. Thus, the temperature gradient models which were suggested in this study may be used as the basis data in calculating the design load temperature.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.77-84
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• 2007

In this paper presented, a design method of sandwich slab bridge of simple supported made by composite materials. Many of the bridge systems, including the girders and cross-beams, and concrete decks behave as the special orthotropic plates. Such systems with sections, boundary conditions other than Navier or Levy solution types, or with irregular cross sections, analytical solution is very difficult to obtain. Thus, Finite Difference Method is used for analysis of the pertinent problem. For the design of bridge made by the composite materials, cross-section is used the form-core shape because of this shape is economical and profitable, and for output of the stress value used F.D.M. Based the experimental of a composite specialist, an equation expressing the rate of decrease of tensile strength of glass fibers based on increase of mass was obtained. From these equations, one can estimate the rate of tensile strength reduction due to increased size. Tasi-Wu failure criterion for stress space is used. Strength-failure analysis procedure, using these reduced tensile strength, is presented.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.51-63
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• 2002

This paper presents a hybrid control strategy for seismic protection of a benchmark cable-stayed bridge, which is provided as a testbed structure for the development of strategies for the control of cable-stayed bridges. This benchmark problem considers the cable-stayed bridge that is scheduled for completion in Cape Girardeau, Missouri, USA in 2003. Seismic considerations were strongly considered in the design of this bridge due to the location of the bridge in the New Madrid seismic zone and its critical role as a principal crossing of the Mississippi river. Based on detailed drawings of this cable-stayed bridge, a three-dimensional linearlized evaluation model has been developed to represent the complex behavior of the bridge. A set of eighteen evaluation criteria has been developed to evaluate the capabilities of each control strategy. In this study, a hybrid control system is composed of a passive control system to reduce the earthquake-induced forces in the structure and an active control system to further reduce the bridge responses, especially deck displacements. Conventional base isolation devices such as lead rubber bearings are used for the passive control design and Bouc-Wen model is used to simulate the nonlinear behavior of these devices For the active control design, ideal hydraulic actuators are used and on $H_2$/LQG control algorithm is adopted. Numerical simulation results show that the performance of the proposed hybrid control strategy is quite effective compared to that of the passive control strategy and slightly better than that of the active control strategy. The hybrid control method is also more reliable than the fully active control method due to the passive control part. Therefore, the proposed hybrid control strategy can effectively be used to seismically excited cable-stayed bridges.