• Title/Summary/Keyword: 교량손상

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An Experimental Study on Dynamic Behavior Evaluation of Transitional Track (접속부 궤도의 동적거동분석을 위한 실험적 연구)

  • Cho, Sung-Jung;Choi, Jung-Youl;Chun, Dae-Sung;Kim, Man-Cheol;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1379-1385
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    • 2007
  • In domestic transitional zone design, there is regulation to prevent generation of irregular substructure behaviors that negatively influence in prevention of plasticity settlement on approach section and contact section as well as relieve overall track rigidity by reducing sectional foundation and track stiffness difference, but design guideline that considers dynamic behavior of transitional track in actual service line is very insignificant. Therefore in this study, characteristics of transitional track dynamic behaviors by substructure stiffness are researched and measured dynamic response of transitional track by substructure stiffness in order to prove correlation between substructure and track and calculate elasticity(stiffness) and track load of transitional track by using measurement and formula to provide basic information for developing design guideline considering dynamic behavior of service line transitional track.

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Flexural Strength Analysis of RC T-Beams Strengthened Using Fiber Sheets (섬유시트로 보강된 T형 철근콘크리트보의 휨 강도 해석)

  • Park, Tae-Hyo;Lee, Gyu-Chul
    • Journal of the Korea Concrete Institute
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    • v.15 no.2
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    • pp.234-245
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    • 2003
  • Most of the concrete bridge structures are exposed to damage due to the excessive traffic loading and the aging of the structure. The damage of concrete causes the further deterioration of the function in the concrete structure due to corrosion of the reinforced bars and decohesion between the concrete and the reinforced bar. The quick rehabilitation of the damaged concrete structures has become of great importance in the concrete structural system in order to avoid the further deterioration of the structures. Recently fiber sheets are used for strengthening the damaged concrete structures due to its many advantages such as its durability, non-corrosive nature, low weight, ease of application, cost saving, control of crack propagation, strength to thickness ratio, high tensile strength, serviceability and aesthetic. However, the lack of analytical procedures for assessing the nominal moment capacity by the fiber sheet reinforcement leads to difficulties in the effective process of decisions of the factors in the strengthening procedure. In this work, flexural strengthening effects by fiber sheets bonded on bottom face of the member are studied for the reinforced concrete T beam. In addition, auxiliary flexural strengthening effects by U-type fiber sheets bonded on bottom and side faces of the member to prevent delamination of the bottom fiber sheet are theoretically investigated. The analytical solutions are compared with experimental results of several references to verify the proposed approach. It is shown that the good agreements between the predicted results and experimental data are obtained.

A Study on the Risk of Lightning in Special Structures and its Verification Method (특수 구조물의 낙뢰 위험도와 검증 방안에 관한 연구)

  • Yoo, Jeong Hyun;Kim, Hei Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.6
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    • pp.664-668
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    • 2018
  • Free-standing structures that are especially high are more likely to receive brain attacks caused by lightning. Since special structures are generally part of national industrial structures, lightning strikes mostly cause socio-economic damage. Lightning protection facilities are installed to prevent such lightning damage, but in 2015, support cables on West Sea bridges were hit by lightning, causing a lot of economic damage. Accordingly, the design of a lightning protection system shall establish protective measures after analyzing the risk of debris falling onto the structure. In this thesis, lightning strikes are analyzed directly in relation to the modeling system that operates the actual information collection system for lightning strikes, depending on the location of the tall, free-standing structures, and practical lightning hazard information is provided by a meteorological station. In addition, we propose monitoring and applying a probability correction rate to the calculation of the lightning risk based on the number of lightning strikes directly reaching the ground in order to obtain an effective lightning risk assessment.

Fatigue Behavior of Steel-Concrete Composite Bridge Deck with Perfobond Rib Shear Connector (유공판재형 전단연결재를 갖는 강-콘크리트 합성바닥판의 피로거동에 관한 연구)

  • Kyung, Kab Soo;Lee, Seung Yong;Jeong, Youn Ju;Kwon, Soon Cheol
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.1A
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    • pp.71-80
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    • 2010
  • Bridge deck is directly influenced by environment and vehicle load, it is easily damaged so that it requires an appropriate repair and retrofit. Therefore, developing a bridge deck with high durability is necessary in order to minimize the maintenance of bridge deck and use it to its design life. In this study, static test was carried out to evaluate a fatigue capacity of steel-concrete composite deck, which was newly developed by supplementing problems of existing reinforced concrete deck. Based on results from the static test, fatigue load was decided, and fatigue test was conducted under the constant amplitude repeated load. From the fatigue tests, the S-N curve regarding principle structural details of composite deck was made, and characteristics of fatigue behavior was estimated by comparing and evaluating it with fatigue design criteria. In addition, fatigue design guideline was presented. As a result, it is found that each structural details of composite deck proposed by this study, such as upper flange of corrugated steel plate and middle section of it, shear connector and lower flange of corrugated steel plate, is satisfying the fatigue strength.

Use of a Genetic Algorithm to Predict the Stiffness Reductions and Retrofitting Effects on Structures Subjected to Seismic Loads (지진하중을 받은 구조물의 유전알고리즘 기반 강성저하 및 보강 효과 추정)

  • Lee, Jae-Hun;Ahn, Kwang-Sik;Lee, Sang-Youl
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.33 no.3
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    • pp.193-199
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    • 2020
  • This study examines a method for identifying stiffness reductions in structures subjected to seismic loads and retrofitting effects using a combination of the finite element method and an advanced genetic algorithm. The novelty of this study is the application of seismic loading and its response to anomalies in the tested structure. The technique described in this study may enable not only detection of damaged elements but also the identification of their locations and the extent of damage due to seismic loading. To demonstrate the feasibility of the method, the advanced genetic algorithm is applied to frame and truss bridge structures subjected to El Centro and Pohang seismic loads. The results reveal the excellent computational efficiency of the method and its ability to prevent severe damage from earthquakes.

Numerical Simulation on the Steel Plate Cutting Performances of Bent-Shaped Charge Holder Blasting (드로잉 가공 성형폭약용기의 강판절단성능에 관한 수치해석적 연구)

  • Min, Gyeong-Jo;Park, Hoon;Oh, Se-Wook;Park, Se-Woong;Suk, Chul-Gi;Cho, Sang-Ho
    • Explosives and Blasting
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    • v.36 no.3
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    • pp.19-28
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    • 2018
  • Locally damaged structures caused by earthquake or extraordinary external forces have been required to rapidly be dismantled because of its possibility of additional collapses. Particularly, steel frame structures were demolished by the shaped charge blasting method. Recently a research suggested a shape charge blasting technique which uses bent-shaped charge holder of copper plate and emulsion explosive charge to cut thick steel plates. This study simulated the cutting performance of the bent-shaped charge holder with considering types of explosives, thickness of copper liner and stand-off distances using LS-DYNA software. The shape charge blasting test of a 25mm thickness steel plate were used to calibrate the input parameters of the numerical models. The penetration depth and penetration width were analysed with different types of explosives, thickness of copper liner and stand-off distances.

Behavior of Stress and Deformation Generated by Repair Welding under Loading (공용중 보수용접에 의한 용접부의 응력 및 변형의 거동 - 인장력 작용중 균열보수용접에 의해 생기는 응력 및 변형의 거동 -)

  • Chang, Kyong-Ho;Lee, Sang-Hyong;Jeon, Jun-Tai
    • Journal of Korean Society of Steel Construction
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    • v.12 no.3 s.46
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    • pp.269-279
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    • 2000
  • It is much expected that steel bridges, which have been damaged by increase of vehicle load and corrosion, need repair or strengthening. In this paper, the stress generated by repair welding under loading are analyzed by three dimensional elasto-plastic analyses. The longer and deeper repair weld line bocemes, the larger the magnitude of transient stress becomes. The magnitude of transient stress generated by repair welding under loading $({\sigma}_y/3,\;{\sigma}_a)$ is similar to summation of stresses generated by repair welding and loading. The longer repair weld line ratio(1/b) becomes, the larger the magnitude of transient stress generated by repair welding under loading bocomes. And, the longer repair weld line ratio(1/b) becomes, the larger the magnitude of in-plane displacement generated by repair welding under loading$({\sigma}_y/3,\;{\sigma}_a)$.

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Stress History Evaluation for Truss Bridge with Local Damages by Using Global-Local Model Combination (전체해석과 국부해석 조합법을 이용한 국부결함이 있는 트러스교 응력이력해석)

  • Kim, Hyo-Jin;Park, Sang-il;Bae, Gi-Hoon;Lee, Sang-Ho
    • Journal of Korean Society of societal Security
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    • v.3 no.1
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    • pp.33-42
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    • 2010
  • This study predicts the stress history for truss bridge with local damages by using global-local model combination method. For this end, the global structure is modeled by 3D frame elements and the selected local details are modeled by shell elements. Then superposition principle enable the global-local model to be combined interactively. Because the frame model cannot consider the rigidity of gusset plate and the interation of structural members due to the complexity of stress distribution in truss connection. The section modification factors are proposed to calibrate the stiffness of global frame element. The global-local model combination is verified by comparing the numerical results with experimental data obtained from the proof loading test to the operating truss bridge. Furthermore, stress histrories of the truss bridge are generated in the consideration of the rigidity of truss connection with local damage by using the combination method.

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Development of Corrosion Detection Method for Closed U-ribs in Steel Bridges Using Ultrasonic Velocity Method (초음파 속도법을 활용한 강교 부식 손상탐지법 개발)

  • Kim, Woo-Seok;Mun, Seong-Mo;Kim, Cheol-Min;Lee, Kang-Moon;Im, Seok-Been
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.6
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    • pp.254-261
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    • 2021
  • This study was intended to develop an inspection method to detect defects in closed-cell steel members in steel girder bridges. The ultrasonic pulse velocity method was selected as a rapid and effective method to identify thickness changes of steel specimens caused by corrsion. This study developed an algorithm to expedite the process and improve the accuracy in the prediction of steel plate thickness. Also, both static and continuous scanning methods were compared to each other to identify the difference in accuracy, but the results revealed that both methods produce almost the same results. This study also provided the idea to calculate the height of water contained in the closed-cell steel member and results of laboratory experimental results. The water heights which is thicker than the steel plate thickness were detectable and predicted using the idea suggested by this study, but the water heights lower than the steel plate thickness were not possible. However, the results showed whether the steel member contains water or not.

Economic Analysis of Concrete Panel Replacement of PSC Bridge with Embedded Demountable Shear Connector (매립형 분리식 전단연결재를 적용한 PSC교 콘크리트 바닥판 교체공사의 경제성 분석)

  • Soon-Hwan, Lee;Jong-Eon, Kim;Jae-Gyu, Kim;Se-Hyun, Park;Dae-Sung, Jung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.376-385
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    • 2022
  • The embedded demountable shear connector was developed in preparation for replacement works due to deterioration and damage to the bridge panel of the PSC girder bridge which is a road infrastructure directly related to the safety and convenience of the people. The demountable shear connector minimizes crushing works in the demolition process of the panel, and it is easy to re-construct the shear connector for replacement work. The economic feasibility of the PSC girder bridge using the embedded demountable shear connector compared to the existing construction method was analyzed from the perspective of road users (people) by calculating and comparing the cost of road users caused by traffic blocking during each construction method.