• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.3 s.18
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• pp.11-21
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• 2005

This study is performed to understand complex behavior and to investigate the rational analysis methods for seismic design of the curved bridges. To analyze the curved bridges for the seismic loadings, it is used that the finite element analysis program has the 7-dof curved beam and straight beam element. The free vibration characteristics of the curved bridges are compared with the straight bridges that have span length same as the average arc length of inside and outside girder of those. For the same case, the dynamic behavior is compared under seismic loadings. It is found that regular bridges classified by AASHTO are analyzed as if those were straight. To investigate the dynamic behavior of general curved bridges under seismic loading, the seismic loading directions and the subtended angle of curved bridges are varied.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.141-142
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• 2017

우리나라와 같이 산악지형이 많은 곳에서는 불가피하게 곡선형태의 교량을 적용해야하는 경우가 빈번하게 발생한다. 또한 곡선교량은 지형적 제약 조건으로 인한 적용 이외 에도 경관적 아름다움으로 인해 많이 건설되고 있는 추세이다. 이러한 곡선 교량의 경우 직선 교량보다 형상적인 문제로 비틀림과 뒤틀림으로 인해 다른 거동 양상을 보이며 특히 동적인 거동에서는 매우 다른 거동 형태를 보인다고 할 수 있다. 따라서 본 연구에서는 곡선 보의 유한요소 모델을 구축하여 정적해석을 수행하고 이를 이론해와 비교하여 검증하고자 하며 결과적으로 구축된 유한요소 모델의 결과와 이론해의 결과와 잘 부합한다고 판단된다.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.806-812
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• 2020

Purpose: This is aimed to evaluate the seismic fragility of curved bridge structure with I-shape girder subjected to 12 high frequency ground motions based on Gyeongju earthquake. Method: The linear elastic finite element model of curved bridge with I-Shape cross section was constructed and them linear elastic time history analyses were performed using the 12 artificial ground motions. Result: It was found that displacement response(LS1, LS2) was failed after PGA 0.1g and the stress response also showed failure after PGA 0.2g. Conclusion: The curved bridge with I-shape girder was sensitive to high frequency earthquakes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.135-144
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• 2006

In performing a risk analysis of structures under earthquakes, it is imperative to identify the vulnerability of structures associated with various damage stages considering structural properties, soil-structure interactions, site condition, and so on. In this paper, the method to derive a representative fragility curve of seismic isolated LRB(lead rubber bearing) bridges is proposed. In which, the curve is assumed log-normally distribution with two parameters. The risk analysis of seismic isolated LRB bridges considering earthquake effects such as PGA, PGV, SA, SV, and SI is also performed to assure the earthquake resisting capability of the structures. An practical way for constructing the representative fragility curves is also recommended combining fragility curves of structures.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.35-47
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• 2003

Seismic ground motion can vary significantly over distances comparable to the length of a majority of highway bridges on multiple supports. This paper presents results of fragility analysis of two actual highway bridges under ground motion with spatial variation. Ground motion time histories are artificially generated with different amplitudes, phases, as well as frequency contents at different support locations. Monte Carlo simulation is performed to study dynamic responses of the bridges under these ground motions. The effect of spatial variation on the seismic response is systematically examined and the resulting fragility curves are compared with those under identical support ground motion. This study shows that ductility demands for the bridge columns can be underestimated if the bridge is analyzed using identical support ground motions rather than differential support ground motions. Fragility curves are developed as functions of different measures of ground motion intensity including peak ground acceleration(PGA), peak ground velocity(PGV), spectral acceleration(SA), spectral velocity(SV) and spectral intensity(SI). This study represents a first attempt to develop fragility curves under spatially varying ground motion and provides information useful for improvement of the current seismic design codes so as to account for the effects of spatial variation in the seismic design of long-span bridges.

• Computational Structural Engineering
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• v.17 no.1
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• pp.7-14
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• 2004

도시 교통의 혼잡을 개선하기 위하여 대도시에서는 고가도로의 건설이 필수적이며, 고가도로 노선 내에서는 교통흐름의 원활화를 위하여 교량 자체의 평면 형상을 도로선형과 일치시켜야 하므로 특히 곡선교의 건설은 필수적이다. 아치교(arch bridge)나 곡선교(horizontally curved bridge)는 교량건설에 있어서 널리 적용되는 구조이며 적절히 설계가 이루어진다면 미관이 뛰어나고 매우 경제적인 교량구조가 될 수 있다. 또한 건설 지점의 입지조건 등에 의해 곡선교의 건설이 불가피한 경우가 많기 때문에 이에 대한 정확한 해석은 매우 중요하다.(중략)

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.626-633
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• 2019

Purpose: The primery objecting of this paper is to explore the seismics fragility of curved bridge based on the change of girder section. Method: The cross section of the bridge structure was constructed with I, T, and Box shapes and then, in order to perform the seismic fragility 24 seismic ground motions were used, including Gyeongju Pohang Earthquake. Result: Fist, T-Shape of the bridge strucrue was much fragility in terms of the stress on girder section, in comparison to the other shapes. The seismic fragilies of the structures with respect to displacement(drift ratio), however, were shown simialr. Conclusion: In other to wvaluation the seismic fragility of curved structure using different girder shapes, analytical models of the structure were constructed and then, the probability failure of box-shape girder was shown lower probability. In further, Parametric studies of curved structures must be conducted.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.161-168
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• 2015

Horizontally curved bridges are subjected to torsional loads by their vertical dead loads only as well as eccentric loads, which cause negative reactions at supports. In this paper, effects of bridge curvature on vertical reactions at supports are investigated for 48.8 m length simple span steel box girder bridges with elastomeric bearings by varying curvature angle from 0.49 to 1.35 rad. In order to expect magnitude and direction of reactions including possibility of negative reactions, reaction evaluation equations have been analytically developed by separating a superstructure of curved bridge into independent components. Concrete slabs and bottom flanges in steel box section are assumed geometrical annular sectors in area dimension, and top flanges and webs that have very narrow projected areas are assumed geometrical arcs in line dimension. Proposed equations have relatively simple forms and prediction values are on very good agreement with those from finite element analyses by difference of 1% order.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.39-42
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• 2010

최근 보행자가 교량의 진동에 의한 불안감을 느끼는 경우가 발생되면서 설계 단계에서 진동에 대한 고려하고 있다. 그러나 설계자는 범용유한요소프로그램에 이동하중을 적용하여 동적응답해석을 하는 것에 어려움을 느끼고 있으며 그 결과 Meister감각곡선에 의한 진동사용성 평가도 정확히 수행되지 않고 있다. 본 연구에서는 설계자들이 수행하는 교량의 진동사용성 평가방법의 간편한 적용을 위하여 이동하중모델 생성툴을 연구하였으며, 범용유한요소프로그램으로 모델링 된 교량의 매개변수를 변화해가며 진동사용성 평가를 수행하였고 연구 결과 중 매개변수의 하나인 보요소의 길이에 따른 진동사용성 평가결과만을 작성하였다. 평가결과 보요소의 길이에 따라 교량에 발생되는 진동과 가속도의 응답치가 다르게 나타났으며, 발생되는 주요주파수 범위도 다르게 해석되었다. 이러한 동적응답의 결과가 다르게 해석되면서 Meister 감각곡선에 의한 평가등급이 차이도 발생되었다. 따라서 정확한 진동사용성 평가를 위해서는 동적응답해석 시 다양한 매개변수에 의한 동적응답의 결과에 대한 연구는 물론 다양한 교량 형식과 그에 맞는 모델링에 대한 많은 연구가 필요할 것으로 사료된다.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.5
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• pp.75-83
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• 2003

The ultimate goal of this research is to improve highway system performance in earthquakes by evaluating the effectiveness of retrofitting bridges with column jacketing. The objective of the study is to determine if steel jacketing increases the ductility capacity of bridge columns and hence improves the fragility characteristics of the bridge. Analytical fragility curves are used to adjust the empirical fragility curves obtained for the unretrofitted bridges using seismic damage data collected following past earthquakes. The adjustment was carried out by increasing the median values of the empirical curves through comparison with the median values of the corresponding fragility curves obtained analytically, both before and after being retrofit.