• International Journal of Concrete Structures and Materials
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• v.6 no.3
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• pp.199-207
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• 2012

Concrete is an economical construction material and for that reason it is widely used in buildings and infrastructures. The use of deicing salts, expansion joint failure, and freeze-thaw cycles have led to concrete bridge girders experiencing corrosion of steel reinforcement and becoming unsafe for driving. The goal of this research is to assess the effectiveness of current and possible repair techniques for the end region of damaged prestressed concrete girders. To do this, three American Association of State Highway and Transportation prestressed concrete girders were tested to failure, repaired, and retested. Three different repair materials were tested including carbon fiber, glass fiber, and surface mounted rods. Each different repair material was also tested with and without injected epoxy. Comparisons were then made to determine if injecting epoxy had a positive effect on stiffness and strength recovery as well as which repair type regained the largest percentage of original strength.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.55-62
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• 2003

This study considered the effect of scour depth on the behaviour of pile foundation of bridge structure under seismic excitation. The numerical model was composed of the superstructure, pile foundation and soil. The superstructure and pile was modeled by beam elements and soil was by spring elements. The pile head and concrete footing was considered as hinge and rigid connected situation, respectively. A toro-gap element was used to model the expansion joint of superstructure. Nonlinear dynamic analysis was carried out on the constructed model. It was acknowledged that the steel pile become to yield after the scour depth reached about 2.0m.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.107-108
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• 2023

본 논문에서는 교량의 변위를 IoT 장치를 이용하여 실시간 측정하고 추출된 데이터를 이용하여 교량의 이상징후를 AI 기반으로 진단 및 모니터링 하는 방법을 제안한다. AI 모델 학습 학습을 위해서 비정상 상태의 교량이 필요하지만, 실제 교량에 인위적으로 비정상 상태를 만들 수 없으므로, 탄성 받침을 이용하여 모의 교량을 제작하였다. 탄성 받침을 이용하여 제작에 반영 및 모의교량에 적합한 모의 차량도 제작하여 정상적 데이터와 비정상적 데이터를 수집하였다. 수집된 데이터를 전처리 과정을 통해 AI 분석을 통해 교량의 이상 징후를 진단 및 모니터링하였으며, 제안 모델을 실험한 결과 96.7%의 정확도가 도출되었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.3
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• pp.167-174
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• 2022

This study investigates the behavior of a jointless bridge that integrates superstructure and abutment without an expansion joint. Based on the sensitivity analyses conducted in previous studies, a shell-based model was determined to be the most suitable numerical analysis model for jointless bridges due to the similarity of the model's results compared with the obtained displacement shape, which was influenced by relative errors, precision, and practical aspects. Accordingly, the behavior of a jointless bridge was analyzed at various wall depths using shell element-based and solid element models. In addition, the results of MIDAS Civil and ABAQUS analysis programs were compared. In the case of semi-integrated bridges (A and B), the displacement decreased as the wall depth increased due to the ground reaction force in Case 1 under a linear spring condition and +30℃. In the case where temperature was -30℃, the change in displacement was small because the ground reaction did not occur. As for bridge C (a fully integrated alternating bridge) and bridge D (an integrated chest wall alternating bridge), the displacement decreased as the wall depth increased at both +30 and -30℃ due to pile resistance. As for the comparison between the analysis programs used, the relative error in Case 1 was small, whereas a significant difference in Case 2 was observed. The foregoing variation is possibly due to the difference in the application of the nonlinear spring in the programs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.361-373
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• 2010

Bridges constructed without any expansion joint or bridge bearing are called integral abutment bridges. They integrate the substructure and the superstructure. Possible deformation of the superstructure, due to changes in temperature for example, is prevented by the bending of the piles placed at the lower part of the abutment. This study examines the behavior of integral abutment bridges through soil-pile interaction modeling method and proposes an appropriate modeling method. Also, it assesses the behavior characteristics of the superstructure and piles of integral abutment bridges through parametric study. Soil condition around the pile, abutment height, and pile length were selected as parameters to be analyzed. Structural analysis was conducted while considering the interactions of soil-pile and temperature change-earth pressure on the abutment. Comparative behavior analysis through soil-pile interaction modeling showed that elastic soil spring method is more appropriate in evaluating the behavior of integral abutment bridges. The parametric study showed the tendency that as the soil stiffness around the pile increases, the moment imposed on the superstructure increases, and the displacement of the piles decreases. In addition, it was observed that as the bridge height increases, the earth pressure on the abutment increases and that in turn affects the behavior of the superstructure and piles. Also, as the length of the pile increased, the integral bridge showed more flexible behavior.

• Journal of the Korean GEO-environmental Society
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• v.19 no.12
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• pp.59-64
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• 2018

The damages to the reinforced earth retaining wall are divided into the front wall, foundation, drainage and upper slope. Damage of reinforced earth retaining wall is mainly caused by damage caused by drainage problem in the field. Recently, damage caused by snow removal materials have been occurred. Recently, the amount of snow removal materials used in winter is increasing due to abnormal weather. This chlorides degrades the concrete structure, where the reinforced earth retaining wall was no exception. There has recently been a case in which the front wall of the reinforced earth retaining wall deteriorates due to the chlorides introduced into the back filling portion through the drainage passage. Therefore, in this study, the cause of damages of reinforced earth retaining wall constructed in bridge abutment was analyzed, and an analytical study was conducted on the countermeasure. As a result, it was found that chlorides, which was introduced through the drainage system in the expansion joint of the bridge shift part or the upper structure, is infiltrated into the back part of the reinforced earth retaining wall and damaged. Therefore, it is suggested to improve the drainage system and restored the stiffness of the front wall.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.255-262
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• 2021

In this study, a jointless bridge that integrates the superstructure and abutment without installing an expansion joint was analyzed. An example of a jointless bridge that has been introduced in Korea since 2009. Owing to the short period of use and lack of experience in design, construction, and maintenance, there is insufficient information regarding the long-term behavior of jointless bridges. When analyzing numerous bridges, the numerical analysis model must maintain the numerical values used and ensure the convenience of model construction. In this study, sensitivity analysis was performed to select a numerical model for various types of jointless bridges using commercial finite element programs, MIDAS Civil and ABAQUS 2018. According to a solid element-based model, we analyzed the mean and maximum relative errors between structural models. Consequently, it was found that the beam element-based model exhibits a significantly small relative error in comparison to the shell element, where a relatively large error was recorded. Therefore, the optimal numerical analysis model, a practical model that maintains the similarity and precision of the displacement shape cause by relative error, was judged to be the most suitable for jointless bridges based on the shell element.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.407-414
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• 2004

Bridges in common use are expected to have more varieties of load in their connected members and bolts than in construction. Faults in connection members or bolts occur so often according to the time flow. One of the purposes of this study is to find out the behavior and structural features of high-tension bolted joints with faults that are very difficult and cost much to find out through experimentation with finite element analysis. Another purpose of this study is to provide sufficient data, estimated experimental results, and the scheme of the test plate for an economical experimental study in the future. Surveys of bridges with a variety of faults and statistical classifications of their faults were performed, as was a finite element analysis of the internal stress and the sliding behavior of standard and defective bridge models. The finite element analysis of the internal stress was performed according to the interval of the bolt, the thickness of the plate, the distance of the edge, the diameter of the bolt, and the expansion of the construction. Furthermore, the analysis explained the sliding behavior of high-tension bolt joints and showed the geometric non-linear against the large deformation, and the boundary non-linear against the non-linear in the contact surface, including the material non-linear, to best explain the exceeding of the yield stress by sliding. A normally bolted high-tension bolt joint and deduction of bolt tension were also analyzed with the finite element analysis of bridge-sliding behavior.

• Journal of Venture Innovation
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• v.2 no.2
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• pp.31-46
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• 2019

Materials and Parts acts as the bridge in the manufacturing industry. In 2018, the materials and parts industry became the leading industry in Korea as its export reached $316.2 billion, accounting for 52.3 percent of the country's total exports. As such, it is the main industry of Korea leading the trade surplus, but when it comes to Japan, it is not. The trade deficit with Japan shrinks to $24 billion last year but the materials and parts industry still accounts for 60 percent of total deficit, which is about $15.1 billion. Today Japan has the top competitiveness in the high-tech materials and parts industry and the factors can be found in cooperation and symbiosis among companies, monotsukuri spirit, and long-term government policy. In order for Korean economy to pursue the Japan's high-tech materials and parts industry, the following change of perception is necessary. First, the material and parts industry requires win-win cooperation. In general, materials and parts are intermediate products. Therefore, it is important to understand the characterist that the transactions are all made up between companies not the with consumers. Second, expansion of joint technology development is absolutely necessary. South Korea is a leading country in the field of general-purpose materials and parts. However, the research shows that South Korea has structure which small and medium-sized companies could have difficulties in developing high-tech products as finding demand and developing market are hard due to low participation of large corporations at R&D stage. It is necessary for large corporations to participate in joint R&D and share opinions of customers from the beginning stage of R&D. Third, a long-term approach is needed. Structural vulnerabilities in the Korea's materials and parts industry, including the lack of advanced technologies is the main reason of solidification of Korea's trade deficit with Japan but there are also cultural differences about technology in the background. Even if it takes time, a long-term approach is absolutely necessary to build up technology and know-how in order to secure competitiveness in the high-tech materials and parts industry. This approach applies to act of corporation and government policy.