• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.773-784
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• 2019

With the recent development of 4th industrial revolution technology, BIM information systems are spreading to civil engineering fields as a link to this technology. Accordingly, the Land, Infrastructure and Transport Ministry is announcing a technical policy to introduce the BIM information system into the construction sector from 2020. Usually, SOC-related facilities are complex, making it difficult to implement BIM without a standards framework. To overcome these problems, it is urgent to develop a BIM standard classification system. In this study, the BIM property classification system was developed to link the previously developed object classification system by analyzing domestic and foreign prior studies and working standards. This includes property information of businesses, facilities, parts of facilities and components that correspond to the level of object composition in the road and river sectors. It also suggested ways to apply expansion to various SOC areas and to organize spatial information by facility. The results of this study were applied to road facilities to verify the possibility of information building. The development of the BIM Standards Classification System through this R&D will contribute to the development of construction IT by providing conditions for convenient modeling and information system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.1-10
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• 2021

In this study, a circular pipe can be installed by suction pressure for construction on soft ground with a low-water level. A series of laboratory-scale model tests were conducted in sandy ground to comprehend the suction pressure of the circular pipe in low-water levels. For repeated tests on saturated sandy soil, a container was mounted with three vibration generators on the floor. A repetitive vibration was applied using the vibration system for ground compaction. In the model tests, different diameters and thicknesses on saturated sandy soil with a water depth were considered. The result showed that the suction pressure increased with increasing penetration depth of the circular pipe. Moreover, the suction pressure required to penetrate the pipe decreased with increasing diameter. In the low-water level, the total suction pressure measured at the top lid increased because additional suction pressure is required to lift the water column. On the other hand, this led to a decrease in suction pressure to penetrate the circular pipe because the weight of the water column is applied as a dead load. Therefore, it is necessary to consider the water level to design the required suction pressure accurately.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.1
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• pp.9-14
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• 2022

In this study, a smart jack-up system was developed to prevent safety accidents by performing risk analysis when a structure is lifted for maintenance. A quantitative risk analysis program that can analyze the risk using the pairwise comparison matrix analysis method was developed. The risk was analyzed in real-time for the lifting structure by connecting the program with an automatic jack-up system. Displacements were measured by the IR sensor among the components of the automatic jack-up system, and the displacements were provided to the quantitative risk analysis program. To confirm the performance of the smart automatic jack-up system, experiments were conducted on bridge and risk analysis was performed when a superstructure was lifted. A linear variable differential transformer (LVDT) was also installed on the bridge to verify the performance of the smart automatic jack-up system. The maximum displacements were measured using the devices, and the declinations were compared. The performance of the simultaneous operation of the jack-up device was verified by the analysis of variance (ANOVA).

• Land and Housing Review
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• v.14 no.3
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• pp.145-155
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• 2023

Recently, with the widespread adoption of Building Information Modeling (BIM) technology in the construction industry, various object detection algorithms have been used to verify errors between 3D models and actual construction elements. Since the characteristics of objects vary depending on the type of construction facility, such as buildings, bridges, and tunnels, appropriate methods for object detection technology need to be employed. Additionally, for object detection, initial object images are required, and to obtain these, various methods, such as drones and smartphones, can be used for image acquisition. The study uses a 360° camera optimized for internal tunnel imaging to capture initial images of the tunnel structures of railway and road facilities. Various object detection methodologies including the YOLO, SSD, and R-CNN algorithms are applied to detect actual objects from the captured images. And the Faster R-CNN algorithm had a higher recognition rate and mAP value than the SSD and YOLO v5 algorithms, and the difference between the minimum and maximum values of the recognition rates was small, showing equal detection ability. Considering the increasing adoption of BIM in current railway and road construction projects, this research highlights the potential utilization of 360° cameras and object detection methodologies for tunnel facility sections, aiming to expand their application in maintenance.

• Korean Journal of Construction Engineering and Management
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• v.24 no.2
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• pp.13-23
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• 2023

Unlike building construction projects, where the activity is repeatedly carried out in a limited area, civil engineering projects such as roads and railroads are carried out in a linear type in a horizontal working space over several tens of kilometers. Each activity is managed with a station number that has a unit of distance from the starting point to the end point. For this reason, since the work location information of the activity is a major management factor, the Gantt chart system that expresses only schedule information may have limitations. In this study, authors propose a method for constructing a linear schedule chart that can simultaneously express schedule information indicating the start and finish dates and location information indicating the start and end positions of each activity, and develop a system for generating a linear schedule chart. In the study, the coordinate axes of the linear schedule chart consisted of distance and date values on the X and Y axes, respectively, and each activity was expressed as a symbol that can infer the type of work to increase the visibility of the linear schedule chart compared to the simple bar chart method. The linear schedule chart generation system was reviewed for practical applicability by utilizing the actual schedule data of bridge structures in a railroad project.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.315-327
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• 2009

In this study, the static test of CFT truss girders for different f/L ratios was conducted to determine how the ultimate strength of the CFT truss girder was affected by different f/L ratios. A total of two CFT truss girders were constructed and tested under bending condition. The length of all specimens is 20,000 mm. The CFT truss girder is a tubular truss composed of chord members made of concrete-filled circular tubes. The main parameter analyzed in the experimental study was the f/L ratio. This factor was experimentally investigated to assess their influence on ultimate strength and stiffness. The test results show that CFT truss girder has good elastic-plastic property and ductility. The presence of the f/L ratios in CFT truss girders alters its ultimate strength because of the global stiffness of the CFT truss girders. The ultimate strength of CFT truss girders increases as the f/L ratio increases. If the f/L ratio of the CFT truss girders increases twofold, the ultimate strengths increase by 80%. The CFT truss girders showed that they retained large deformation capacity, even after reaching the ultimate strength. Results of this investigation demonstrated the potential for efficiently using a CFT truss as a bridge girder.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.111-120
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• 2009

A local scour around a bridge pier is known as one of important factors of bridge collapse. Two approaches are usually used in estimating a scour depth in practice. One is to use empirical formulas, and the other is to use computational methods. But the use of empirical formulas is limited to predict a scour depth under similar conditions to which the formulas were derived. Computational methods are currently too expensive to be applied to practical engineering problems. This study presented the application of artificial neural networks (ANN) to the prediction of a scour depth around a bridge pier at an equilibrium state. This study also investigated various ANN algorithms for estimating a scour depth, such as Backpropagation Network, Radial Basis Function Network, and Generalized Regression Network. Preliminary study showed that ANN models resulted in very wide range of errors in predicting a scour depth. To solve this problem this study incorporated cluster analysis into ANN. The incorporation of cluster analysis provided better estimations of scour depth up to 42% compared with other approaches.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.98-106
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• 2024

Due to advancements in construction technology and analytical tools, an increasing number of cable-stayed bridges have been designed and constructed in recent years. A cable is a structural element that primarily transmits the main load of a cable-stayed bridge and plays the most crucial role in reflecting the overall condition of the entire bridge system. In this study, a vision-based method was applied to estimate the tension of the stay cables located at a long distance. To measure the response of a cable using a vision-based method, it is necessary to install feature points or targets on the cable. However, depending on the location of the point to be measured, there may be no feature points in the cable, and there may also be limitations in installing the target on the cable. Hence, it is necessary to find a way to measure cable response that overcomes the limitations of existing vision-based methods. This study proposes a method for measuring cable responses by utilizing the characteristics of cable shape. The proposed method involved extracting the cable shape from the acquired image and determining the center of the extracted cable shape to measure the cable response. The extracted natural frequencies of the vibration mode were obtained using the measured responses, and the tension was estimated by applying them to the vibration method. To verify the reliability of the vision-based method, cable images were obtained from the Hwatae Bridge in service under ambient vibration conditions. The reliability of the method proposed in this study was confirmed by applying it to the vibration method using a vision-based approach, resulting in estimated tensions with an error of less than 1% compared to tensions estimated using an accelerometer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.3
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• pp.21-29
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• 2023

In this study, the stress characteristics of temporary fixed steel rods were analyzed in the "temporary fixing system using internal prestressing tension", which is mainly applied to the construction of superstructures by FCM. It was difficult to confirm the changes in initial tensile force in this system because the steel rod was internally connected to the pier and the PSC BOX. Therefore, measurement was performed before and after the completion of each segment using an FBG sensor to measure the change in the micro length of the steel rod. The results of the analysis showed that 75% to 90% of the maximum vertical contraction of the steel rod that occurred until the completion of the cantilever segment occurred in the fixing ~ 1segment, and the maximum loss of initial prestressing force was 39%. Such excessive loss of tension force to 1 segment means that tension is needed to improve the precision of construction during the fixation, and re-tension is needed to secure stability for conduction of cantilever segments after the completion of 1segment. In the 2 ~ last segment, the stress of the steel rod decreased gradually, and in the summer, the decrease in stress tended to partially recover due to the increase in the length of the steel rod corresponding to the increase in the vertical volume of PSC BOX. The dominant factor in the stress change in 2~ last segment in this phenomenon is judged to be the change in the length of the steel rod according to the temperature. Unlike the change in length, the relaxation was 1.2-2.7%, which was mostly offset by the opposite stress corresponding to the temperature stress. Therefore, a plan was proposed to improve the internal stress, such as adjusting the fixation time.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.137-145
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• 2006

Recently, the interests in structural monitoring of civil infrastructures are increased. Especially, as the civil infrastructures such as bridges, tunnels and buildings become large-scale, it is necessary to monitor and maintain the safety state of the structures, which requires smart systems that can supply long-term monitoring during the service time of the structures. In this paper, we investigated the possibilities of fiber optic sensor application to the various structures. We investigate the possibility of using fiber optic Bragg grating sensors to joint structure. The sensors show good response to the structural behavior of the joint while electric gauges lack of sensitivity, durability and long term stability for continuous monitoring. We also apply fiber optic structural monitoring to the composite repaired concrete beam structure. Peel-out effects is detected with optical fiber Bragg grating sensors and the strain difference between main structure and repaired carbon sheets is observed when they separate each other. The real field test was performed to verify the behaviors of fiber Bragg grating sensors attached to the containment structure in Uljin nuclear power plant in Korea as a part of structural integrity test which demonstrates that the structural response of the non-prototype primary containment structures. The optical fiber Bragg grating sensor smart system which is the probable means for long term assessments can be applicable to monitoring of structural members in various civil infrastructures.