• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.135-146
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• 2019

In this paper, the preventive maintenance strategy in operation stage of a bridge using Bayesian inference is proposed. The proposed technique can be used to predict the variation in the performance (or condition) of the bridge with higher accuracy, considering the uncertainty of monitoring. The applicability of the proposed method to the existing bridges is verified and analyzed that have an advantage in terms of maintenance cost efficiency compared to the conventional periodic maintenance system, which establishes maintenance after damage. It is expected that the proposed preventive maintenance method can be used to overcome the limitation of the conventional periodic maintenance method and to make practical bridge maintenance decision.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.88-89
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• 2011

풍하중이 작용하는 교량의 응답을 구하기 위하여 RFA(Rational Function Approximation)와 같은 시간 영역해석법이 널리 사용되고 있다. 교량 단면의 공기역학적 특성을 정의하는 플러터 계수는 주파수 영역에서 정의되기 때문에, 시간 영역해석을 위하여 inverse Fourier transform을 통해 얻어진 impulse response function을 이용한 중첩 적분법이 제안되었다. 시간 영역해석을 위해서는 플러터 계수에 상관성이 존재해야 함을 밝히고, 최적화 방법을 이용하여 시간 영역 해석을 위한 플러터 계수 산정법을 제안하고자 한다. B/D=20의 구형 단면에 적용하여 제안한 방법의 타당성을 검증하고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.223-231
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• 2008

This research presents a new maintenance planning method for deteriorating bridges considering simultaneously the minimization of the maintenance cost and maximization of the bridge performance. Optimal maintenance planning is formulated as a multi-objective optimization problem that treats the maintenance cost as well as the bridge performance such as the condition grade of the bridge deck, girder and pier. To effectively address the multi-objective optimization problem and decision making process for the obtained solution set, we apply a genetic algorithm as a numerical searching technique and adopt a preference-based optimization method. A numerical example for a typical 5-span prestressed concrete girder bridge shows that the maintenance cost and the performance of the bridge can be balanced reasonably without severe trade-offs between each objectives.

• Composites Research
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• v.17 no.3
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• pp.23-28
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• 2004

A method of calculating the natural frequency corresponding to the first mode of vibration of beams and tower structures, with irregular cross sections and with arbitrary boundary conditions was developed and reported by Kim, D. H. in 1974. In this paper, the result of application of this method to the three span continuous reinforced concrete bridge with elastic intermediate supports is presented. Such bridge represents either concrete or sandwich type three span bridge on polymeric supports for passive control or on actuators for active control. The concrete slab is considered as a special orthotropic plate. Any method may be used to obtain the deflection influence surfaces needed for this vibration analysis. Finite difference method is used for this purpose, in this paper, The influence of the modulus of the foundation and $D_{22}$, $D_{12}$, $D_{66}$ stiffnesses on the natural frequency is thoroughly studied.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.2
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• pp.20-25
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• 2011

In this paper, two dimensional concrete slabs for a railroad bridge were analyzed by the specially orthotropic laminates theory. Both the geometrical and material property of the cross section of the slab was considered symmetrically with respect to the neutral surface so that the bending extension coupling stiffness, $B_{ij}$ = 0, and $D_{16}=D_{26}=0$ Bridge deck behaves as specially orthotropic plates. In general, the analytical solution for such complex systems is very difficult to obtain. Thus, finite difference method was used for analysis of the problem. In this paper, the finite difference method and the beam theory were used for analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.113-120
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• 2008

This study presents the ULMM(unstrained-length-modification method) to determine the cable tension consistent with target tension after arrangement of cable-members by controlling the unstrained length of cables. This method used to be shown to determine the exact unstrained length for cable-supported bridge with elastic catenary cable. The some verification examples show to determine the unstrained length that satisfies the target tension and to obtain the satisfactory result for cable-supported bridge. Accordingly this modification method of the unstrained length in this study is used to introduce the satisfactory target tension.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.17-27
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• 2014

Numerical model became one of most important tools for identifying the state of an existing structure in accordance with development of numerical analysis techniques. A numerical model should be updated based on the measured responses from the existing structure to accurately use the model for identifying the state of the bridge and executing numerical experiments. In this study, a new model updating method based on repetition method without a differential function is introduced and applicability for high speed railway bridge is verified with dynamic stability analysis. A fine measurement based on measurement points roaming method was executed with an wireless measurement system for precise dynamic characteristic analysis. The natural frequencies and mode shapes were estimated by correlation analysis and a mode decomposition technique. An initial numerical model was constructed based on design drawings and the model have been updated in accordance with the introduced model updating method. The results from numerical experiment and field test have been compared for verifying the applicability of the model updating method. And the dynamic stability analysis has been executed to verify the usability of the updated numerical model and the model updating method. It seems that the model updating method can be used for various bridges after evaluation of applicability for other type bridges in further studies.

• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.13-23
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• 2022

The ground-structure interaction of the bridge foundation has been pointed out as a major factor influencing the behavior of the bridge during earthquakes. In this study, the effect of characteristics of ground and bridge foundation on the earthquake vulnerability is investigated. From the pseudo-static analysis, it is confirmed that non-linearity becomes lesser and horizontal load becomes greater when surcharge is considered. It is also found that as the ground worsens and the size of foundation decreases, horizontal load reduces. To derive reasonable structural model for bridge foundation, fragility curve is obtained considering four conditions (fixed condition, equivalent linear condition, non-linear without surchage condition, non-linear with surcharge condition) and compared. Seismic analysis is performed on single pier with Opensees. From the earthquake vulnerability analysis, it is found that shallow foundation can be assumed as fixed condition. In conservative approach, stiffness of spring can be obtained based on Korean highway bridge design code for pile foundation which can consider the ground condition.

• 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 Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.639-642
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• 2011

이 연구에서는 완전 조립식 교량 하부구조의 비선형해석을 위한 전산플랫폼을 개발하였다. 완전 조립식 교량 하부구조의 비선형거동을 정확하게 파악하고 합리적이면서 경제적인 설계기준의 개발을 위한 자료를 제공하는데 그 목적이 있다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 사용된 부착 또는 비부착 텐던요소는 유한요소법에 근거하며 프리스트레스트 콘크리트 부재의 콘크리트와 텐던의 상호작용을 구현할 수 있다. 그리고 접합면요소는 세그먼트 접합부의 비탄성거동을 예측할 수 있다. 제안된 해석기법은 수치예제에 대하여 비선형거동을 비교적 정확하게 예측하였다.