• Journal of Korean Society of Disaster and Security
• /
• v.16 no.2
• /
• pp.75-83
• /
• 2023

In general, bridges are facilities installed for the purpose of easily passing through sections such as valleys and rivers. Railway bridges that run through downtown areas are damaged due to external factors such as earthquakes and collisions with passing vehicles, resulting in serious human casualties. This can cause serious human and properties damage, such as functional paralysis in downtown areas. Depending on the degree of damage, repair work such as partial repair or full replacement is in progress for the bridge where the collision occurred. When damage or deformation occurs due to collision, the repair method is determined according to the degree of deformation and the degree to which the load capacity of the bridge is affected by the deformation. In this study, a numerical analysis review was performed on the repair work for the local deformation caused by the collision of a vehicle on an old railway bridge installed and in operation in an urban area. To this end, a structural safety review of the bridge for local deformations caused by vehicle collisions was conducted. In this paper, a repair method for the accident bridge was presented based on the analysis results.

• Computational Structural Engineering
• /
• v.1 no.1
• /
• pp.113-122
• /
• 1988

A practical model for predicting the risk of fatigue failure of steel highway bridges is developed in this study. The proposed model is derived from fatigue reliability methods by incorporating various factors which may affect the fatigue life of bridges. The fatigue reliability function is assumed to follow the Weibull distribution. The computational form of the Weibull is adopted from Ang-Munse's approach that includes all the statistical uncertainties of the fatigue life of steel members and the stress ranges under variable amplitude loadings. The model accounts for the variation in ADTT, the change in stress history and the effects of inspections, which may occur during the serivce life of bridges. Stress range histograms are collected from the random stress spectra based on the field measurements of an existing bridge, and, thus, the resulting stress range frequency distribution is modelled with a beta distribution. The results of applications of the proposed fatigue analysis methods to an existing bridge show that the proposed models with the computer program developed for numerical computations can be used as a practical tool for the fatigue rating or for the predictions of the remaining fatigue life of deteriorated existing steel bridges.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.5
• /
• pp.35-40
• /
• 2010

The present study proposes the strengthening method to use Conclinic Advanced FiberWrep(CAF) so as to improve Load Carrying Capacity of the RC slab bridge. In order to evaluate the strengthening performance, we strengthen 50cm per unit-width of CAF to the slab's bottom of the test bridge that designed with DB 18, then perform Static and Dynamic Field Load Test. As a result of this, 14.7% of the maximum displacement, 5.0% of the strain and 33.7% of the impact factor are reduced after strengthening. At the middle of the test spans, nominal resisting ratio is increased by 27% and Service Load Carrying Capacity is increased by 44.6%, 48.9% of each span 1 and 2. In conclusion, this study indicates that the strengthening method using CAF is very effective to improve the deteriorated RC slab bridge designed with DB 18, to the DB 24 of the first class bridge design load.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.5
• /
• pp.48-59
• /
• 2019

In recent years, the type of bridge where cables such as suspension bridge and cable-stayed bridge are the main factors in the construction of long-range bridges has been soaring. The effects of cables on these structures are very large, and for structural analysis, it is necessary to study the cable and the structural changes according to the mode characteristics of the cables. In particular, cables are directly connected to camber adjustment, which conveys load effects on girders to tower, and are important components in the overall structure, and since the initial tension on the construction is compared with the tension over time, this study was conducted to help identify the condition of the bridge's aging and abnormalities. Therefore, in this study, the characteristics of the mode from the mode analysis through the impact hammer to the mass of the cable and the change in the length of the cable are analyzed.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.1
• /
• pp.67-74
• /
• 2021

This paper evaluated the structural safety of an aging PSC I-girder bridge with rebar corrosion in the deck. The geometry and rebar of the bridge were designed based on an actual PSC I-girder bridge, and the numerical analysis was performed considering the crack of concrete and yielding of steel rebar. According to the evaluation criteria of Korea Infrastructure Safety and Technology Corporation, this study defined two criteria of rebar exposure and corrosion rates to construct a total of 32 corrosion scenarios. Rebar exposure was defined as the exposure of tensile rebars in the bridge deck due to the removal of cover concrete. The results of the analysis showed that the safety and rating factors of the bridge decreased with increasing rebar exposure and corrosion rates. For the rebar corrosion rate more than 50%, the safety grade of the bridge should be carefully evaluated for all the rebar exposure rate. When the rebar corrosion rate exceeds 57%, the bridge was evaluated as E grade regardless of rebar exposure rate. A correlation analysis for a 2% of rebar exposure rate found that the bridge was evaluated as A grade up to 55.8% corrosion rate, C grade up to 56.9%, D grade up to 58.5%, and E grade for corrosion rate greater than 58.5%. This study indicates the necessity of a quantitative evaluation of rebar corrosion for evaluating the structural safety of aging bridges.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.4
• /
• pp.231-241
• /
• 2021

Although the deterioration of bridges may occur due to various causes, one of the representative causes is that the chloride used for deicing in the winter penetrates bridge members and results in corrosion. This study aims to quantify the ageing degree resulting from the corrosion of a bridge, apply it to the inelastic dynamic analysis model of the bridge, perform a seismic fragility analysis, and evaluate the relationship between the ageing degree and the seismic fragility curve. It is important to appropriately define the threshold values for each damage state in seismic fragility analyses considering the ageing degree. The damage state was defined using the results of existing experimental studies on the characteristics of the deterioration in the displacement ductility capacity of the pier, according to the ageing degree. Based on the seismic fragility analyses of six types of bridges divided by three types of bearing devices and two pier heights, it was found that the seismic vulnerability tends to increase with the ageing degree. The difference in seismic vulnerability with respect to the ageing degree exhibits a tendency to increase as the damage state progresses from slight to moderate, severe, and collapse.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.298-298
• /
• 2019

과거에 경험하지 못한 집중호우가 빈번하게 발생하고 규모가 큰 태풍의 내습이 발생하고 있다. 2018년 7월23일 발생한 라오스 댐붕괴 발생으로 인해 6,600명의 이재민이 발생하였으며, 2008년 중국 쓰촨성 지진에 의해 댐 수백개가 균열이 발생하는 위험한 상황에 이르는 등 댐 붕괴에 따른 대규모 재난의 위험상황은 항시 존재하고 있다. 는 상황에서 댐의 붕괴에 대한 많은 연구가 진행되었다. 이러한 댐 붕괴 상황에 대한 대비책으로 저수지 댐의 안전관리 및 재해예방에 관한 법률 제3조와 자연재해 대책법 제37조에 총저수용량 30만톤 이상의 저수지에 대해 비상대처계획 수립을 하도록 되어 있다. 최근 경주와 포항에서 발생한 규모 5.4이상의 지진이 발생하여 지진에 의한 재난의 위험이 가중되고 있는 상황에서 지진에 의한 댐붕괴에 대한 적절한 시나리오와 분석이 필요하다. 지금까지의 지진붕괴에 의한 EAP의 작성은 단순히 만수위 상태에서 댐의 붕괴시간이 급격히 붕괴되어 범람되는 분석을 하였다. 그러나 지진에 의한 댐의 붕괴에 이르는 지진의 규모는 댐 주변의 건축물, 교량, 심지어 대피소도 붕괴 및 범람에 안전할 수 없는 상황에 이르게 될 것이다. 그러나 현재의 EAP는 단순 범람만을 통해 위험도를 나타내는 것으로 작성되어 있어 이에 대한 수정이 필요하다. 본 연구에서는 지진에 의한 댐 붕괴 EAP 작성시 고려되어야 할 건물의 노후도, 교량, 공공시설물 등이 붕괴될 위험을 판단하고 이에 따른 범람도면의 작성과 시나리오가 작성되어야 한다. 이를 위한 행정안전부에서 제시된 지진 시 댐 붕괴 조건에서 고려되어야 할 시나리오의 구성요소에 대해 검토하였다.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.480-493
• /
• 2007

Many railway-advanced countries are using the various types of track to reduce the track maintenance and repair cost according to the improvement of velocity. It spends on much maintenance and repair cost for ballast track due to abrasion of ballast, track irregularity and unisotropical ballast-support stiffness. The ballast track on railway bridge is accelerating the deterioration of ballast according to interaction of railway bridge and track. As continuing the deterioration, it is caused dynamic loads. Due to these effects, it increases negative loads of track and bridge. However, when designing the railway bridge, the effect of ballast track was applicate only dead load, so elastic behavior effect of ballast track is not influenced. Therefore, this paper presumes the stiffness of ballast track on railway bridge considering dynamic behavior of railway bridge, it was evaluated that effect on dynamic behaviors of railway bridge according to ballast track stiffness.

• Journal of Wetlands Research
• /
• v.22 no.1
• /
• pp.31-38
• /
• 2020

Weirs are to secure amount water of streams and drop structures are to enhance stabilization of stream bed and bridges are to connect isolated region, which are called stream crossing structures. In the stream design criteria, directions for minimum size of structures are suggested to secure stability of stream crossing structures. However the sizes of almost all existing weirs and drop structures are not satisfied with the stream design criteria and only 22 percent of the peirs of bridges are satisfied. To enhance hydraulic stability of existing weirs and drop structures, it is required that the ratio of bed protection to apron should be above 3.3. According to factual survey of structures in the sample streams, it has been shown that the longitudinal slope of rapid works with 1:20 is the most reasonable to design velocity if existing weirs and drop structures are rehabilitated into rapid works. It has been known that violating freeboard and span length of piers should make existing bridges reconstructed or removed. However, comprehensive review including deterioration level of bridges, special regulation for span length, etc. should be considered to determine rehabilitation plan of bridges. In this study, a procedure has been suggested to improve hydraulic stability of weirs, drop structures and piers of bridges. Sound environment of stream and reduction of natural disaster could be achieved by improving stability of cross structures, which could be obtained by governmental budget and active stream management including observance of design criteria.

• Journal of the Korea Concrete Institute
• /
• v.19 no.6
• /
• pp.755-762
• /
• 2007

For the evaluation of the load carrying capacity of the deteriorated PSC I girder bridge in service load state and the verification of the grade to the reinforcement effect of actual bridge strengthened by external prestressing tendons, the field test using vehicles is applied widely. Because this teat was executed in elastic range, the investigation of the characteristics of behavior caused by live load is only available. And it is impossible to estimate load carrying capacity in limit state and nonlinear behavior after that a crack is appeared. In this study, the 27-year-old prestressed concrete girder bridge is used and various load tests are performed, so we evaluate the behavior characteristics of the bridge in service load state and ultimate load state, and estimate the load carrying capacity of bridge. In addition, the artificial damages are induced from cutting internal tendons, and external tendons is added to strengthen it as much as vanished internal tendons. Next we compare the damage state with the strengthening state. In case of the application of external prestressing method to PSC I girder bridge, the present experiment result may decide more exactly the load carrying capacity of actual bridge, the amount for reinforcement, and the standard of quality control etc. at reinforcement work.