• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.224-229
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• 2010

Collision fragility analysis of offshore bridge by ship was performed. Collision velocity and angle were chosen as random variables then collision of 18,000DWT and 30,000DWT ships with bridge was analyzed. Displacement response surface of bridge by ship collision was estimated by varying ship velocity from 2 m/s to 7 m/s. Using the result of reliability analysis, fragility curves of collision was established and risk of offshore bridge to collision velocity as median and log-standard deviation was presented.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.4
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• pp.57-65
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• 2009

This study is an evaluation of seismic fragility function using the HAZUS program for railway bridge systems, based on the results of previous research on seismic safety factor. First, a fragility function for each of the bridge members was evaluated according to the damage criteria and failure mode. Subsequently, bridge system fragility was evaluated using a fault tree to describe damage status. Finally, a fragility evaluation method for the bridge system was developed, based on the safety factor derived from the previous research.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.417-426
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• 2005

Recent days composite bridge dock is gaining attraction due to many advantages such as light weight, high strength, corrosion resistance, and high durability. In this study, composite deck models of hat, box and triangular section type wore fabricated with VARTM Process. For these models, three point flexural tests wore carried out both in strong and weak axis. The experimental results were compared with each other to determine efficient section profile. It has been demonstrated that composite sandwich deck has strong potentials to be used as bridge deck in the new construction and rehabilitation works.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.577-584
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• 2019

Recently, CSB(Cable-Stayed Bridge) have been attempted to be atypical forms for landscape elements in Korea. CSB with new geometry need to analyze their characteristics clearly to ensure structural safety. This study's bridge is the S-shaped curved pedestrian CSB that has a girder with S-shape plane curve and reverse triangular truss cross section, inclined independent pylon, modified Fan type main cable and vertical backstay cable. Curved CSB can have excessive lateral displacement and moment when the tension is adjusted, focusing only on longitudinal behavior, such as a straight CSB. In order to analyze the effect of the cable on the lateral behavior of bridges, the cable is divided into two groups according to the lateral displacement direction of the pylon due to tension. The influence of the combination ratio of GR1 and GR2 on the girder, bearing, pylon, and vertical anchor cable was analyzed. When the tension applied to the bridge is 1.0GR1 plus 1.0GR2, In the combination of 1.2GR1 plus 0.8GR2, the stress on the left and right upper member of the truss girder and the deviation of the both were minimized. In addition, the horizontal force of the bearing, the lateral displacement and moment of the pylon, and the tension of the vertical backstay cable also decreased. This study is expected to be used as basic data for determination of tension of CSB with similar geometry.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.1
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• pp.17-26
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• 2009

The capacity spectrum method (CSM), which is known to be an approximate technique for assessing the seismic capacity of an existing structure, was originally proposed for simple building structures that could be modeled as single-degree-of-freedom (SDOF) systems. More recently, however, CSM has increasingly been adopted for assessing most bridge structures, as it has many practical advantages. Some studies on this topic are now being performed, and a few results of these have been presented as ground-breaking research. However, studies have until now been limited to symmetrical straight bridges only. This study evaluates the practical applicability of CSM to the evaluation of irregular curved bridges. For this purpose, the seismic capacities of 3-span prestressed concrete bridges with different subtended angles subjected to some recorded earthquakes are compared with a more refined approach based on nonlinear time history analysis. The results of the study show that when used for curved bridges, CSM induces higher inelastic displacement responses than the actual values, and that the gap between the two becomes larger as the subtended angle increases.

• Journal of the Society of Disaster Information
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• v.14 no.1
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• pp.43-50
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• 2018

This study presented 3D Finite Element (FE) analysis of curved beam structures subjected to static and dynamic loading conditions, which is particularly strong ground motions. It was shown that the results obtained from 3D FE analyses was similar to the theoretical solution within 1% convergency error, in order to validate the 3D solid FE models in this study. In particular, it was focusing on development of dynamic characteristics of curved beam structures subjected to three-different seismic ground motions: GyeongJu, Lomaprieta and Northridge earthquakes. Consequently, It was interesting to find that the results obtained from GyeongJu earthquake was detuned due to high frequency effect, but the Von-Mises of the curved beam structure under Lomaprieta earthquake was 647.824 MPa at 45 curvature degree.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.946-946
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• 2012

현재 국내 하천의 설계홍수량은 하천정비 기본계획이나 유역종합 치수계획 등을 통하여 고시 되고 있다. 이러한 설계홍수량은 홍수량 산정 지침에 따라 산정되며, 최종적으로 결정된 설계홍수량을 기준으로 하도계획이나 교량, 암거 등의 설계를 실시하였다. 현재 많은 수의 홍수조절용 다목적 댐과 강변저류지 등 각종 수리조작 구조물들이 축조되면서부터 홍수량을 시간별로 조절할 수 있게 되었지만, 미계측 유역에서는 유역의 유출량을 예측하기가 쉽지 않기 때문에 수리조작 구조물들의 효과를 예상하고 조작 및 운영방법을 결정하기 어려운 실정이다. 이러한 이유로, 본 연구에서는 미계측 유역 내 축조하는 수공 구조물의 최적 설계 및 운영방법 결정을 위하여 설계홍수량과 함께 합성단위도법을 적용한 수문곡선을 적용할 수 있도록 Nash 모형을 이용하였다. 유역의 유출특성이 반영된 대표단위도를 산정하기 위해 여러 유역의 다양한 형상계수를 이용하여, 도달시간과 첨두유량에 관한 회귀식을 산정하였다. 이렇게 산정된 회귀식을 여러 형태의 유역과 강우-유출 사상에 적용하여, 미계측 유역의 특정지점에서 발생의 개연성이 충분하고 수공구조물의 설계와 효과에 가장 중요하게 영향을 미칠 수 있는 설계홍수수문곡선을 도출하는 것을 목적으로 하였다. 본 연구의 결과로 나타나는 대표홍수수문곡선을 미계측 유역에 적용한다면 미지의 설계홍수량을 추정함과 동시에 설계홍수량에 상응하는 수문곡선을 도출하여 수공구조물 설계에 이용할 수 있을 것이라 기대한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.947-947
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• 2012

현재 국내 하천의 설계홍수량은 하천정비 기본계획이나 유역종합 치수계획 등을 통하여 특정 빈도의 단일 홍수량의 형태로 고시되고 있다. 이러한 설계홍수량은 홍수량 산정 지침에 따라 산정되며, 최종적으로 결정된 설계홍수량을 기준으로 하도계획이나 교량, 암거 등의 설계를 실시하였다. 하지만 많은 수의 홍수조절용 다목점 댐과 강변저류지 등 각종 수리조작 구조물들이 축조되면서부터 홍수량을 시간별로 조절할 수 있게 되었다. 따라서 종전과 같이 단일 설계홍수량 값만으로는 신설되는 수리조작 구조물의 최적 규모 및 운영방법을 결정하는데 어려움이 있다. 이러한 이유로, 본 연구에서는 Nash 모형을 사용하여 특정유역의 유출특성이 반영된 대표단위도를 산정하고 여러 가지 형태의 강우사상에 적용하여, 유역의 특정지점에서 특정홍수량에 대하여 발생의 개연성이 충분하고 수공구조물의 설계와 효과에 가장 중요하게 영향을 미칠 수 있는 설계 홍수수문곡선을 산정하는 것을 목적으로 하며, 일련의 과정을 프로그램화 시켜 실무적으로 활용될 수 있도록 하였다. 본 연구의 결과로 나타나는 설계홍수수문곡선은 곡선의 첨두부와 형상에 따라, 동일한 규모의 수공구조물 일지라도 그 효과가 달라지기 때문에 수공구조물의 효과를 최대로 하기위한 구조물 형태와 조작 및 운영방법을 결정하는데 도움이 될 것이다.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.3
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• pp.1-10
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• 2010

The target performance of a current seismic design code is to achieve collapse-prevention in order to minimize casualties. Existing structures are also being retrofitted to meet this target performance. This seismic performance seems to have been achieved in recent great overseas earthquakes, but the accompanying enormous economic loss is pointed out as a new problem. A new seismic design concept over the current target performance is required to reduce economic loss, in which a target performance is determined by the damage probability in order to control the damage levels of structures. In this study, the seismic behavior of bridges having different characteristics was investigated by nonlinear seismic analyses, and fragility curves with respect to a reference damage level were derived. Based on these results, the characteristics of target ductilities satisfying a target damage probability were investigated.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.15-21
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• 2009

The design of the stud shear connector of a bridge structure is mostly controlled by the fatigue resistance not by the strength, if it is followed by AASHTO LRFD Bridge Design Specification. This fatigue design code in AASHTO LRFD is based on the research work done by Slutter and Fisher in 1966. These tests seemingly underestimated the fatigue resistance of connectors because of the inherent eccentricity of the one-face test setup which results additional tension forces to the stud. In addition, the stress ranges were not plotted in the log scale, because it was not known at that time that the fatigue resistance of the welded steel structures has a linear relationship of log scales of stress range and number of loading cycles. This study evaluates the test data produced by the Slutter and Fischer, and plot the data on the proper manner. The fatigue push-out test data produced recently by many other researches all around the world are gathered and analyzed, furthermore a design curve is recommended.