• Structural Monitoring and Maintenance
• /
• v.1 no.1
• /
• pp.69-87
• /
• 2014

A new output only modal analysis method is developed in this paper. This method uses continuous wavelet transform to modify a popular blind source separation algorithm, second order blind identification (SOBI). The wavelet modified SOBI (WMSOBI) method replaces original time domain signal with selected time-frequency domain wavelet coefficients, which overcomes the shortcomings of SOBI. Both numerical and experimental studies on bridge models are carried out when there are limited number of sensors. Identified modal properties from WMSOBI are analyzed and compared with fast Fourier transform (FFT), SOBI and eigensystem realization algorithm (ERA). The comparison shows WMSOBI can identify as many results as FFT and ERA. Further case study of structural health monitoring (SHM) on an arch bridge verifies the capability to detect damages by combining WMSOBI with incomplete flexibility difference method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.602-607
• /
• 2003

Sensors based bridge monitoring system (SBBMS) is designed to perform real-time monitoring and to store the performance history of in-service bridges. In general, visual inspections play a major role in maintenance of in-service bridges; however, they are not adequate to document the behavior of a bridge. Therefore, visual inspections and sensor based monitoring systems complement each other. Sensor based bridge monitoring systems consist of hardware and software systems. The hardware system contains the sensors and data-loggers to measure the behavior of a structure, the communicational equipment to transmit the measured data from the site to the monitoring center, and the computers to arrange and analyze the data. The software system controls data-loggers, arranges and analyzes the measured data, makes real-time display, stores the performance history.

• Journal of the Korean Society of Safety
• /
• v.24 no.6
• /
• pp.79-85
• /
• 2009

This study presents an algorithm to select the best alternative plane among various bridge superstructure types(Steel box girder, Rational girder, PSC-I girder) using Value Engineering(VE). Economical efficiency, landscape, constructability, maintenance, stability, function of bridge superstructure were taken into consideration in the designing of bridge. Economical efficiency was evaluated for each alternative plan with optimal design considering Life Cycle Cost(LCC). Repair and rehabilitation histories and some factors were set to get reasonable results. In the application of Analytic Hierarchy Process(AHP), consistency of Pairwise Comparisons Matrix was evaluated and the best plan was determined.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1720-1721
• /
• 2007

This paper presents a Fuzzy+PID control method for a Bridge Inspection Robot(BIR) system. The BIR has been developed with the aim of checking the safety status of a real bridge, gathering accurate data and performing maintenance. The developed robot system is composed of the specially designed car for bridge inspection, the guide rail and the inspection robot. The proposed Fuzzy+PID controllers are used to track speed reference signal of X axis and position reference signal of Z axis. Experimental results verify that the proposed Fuzz+PID control design method can achieve favorable control performance with regard to external disturbance.

• International journal of steel structures
• /
• v.18 no.4
• /
• pp.1219-1241
• /
• 2018

This study aims towards the improvement of a reinforced concrete rigid-frame bridge in an effort to reduce the construction and maintenance costs, and achieve an improved seismic performance. Correspondingly, a new structural rigid connection is proposed for H-shaped steel girders and reinforcing bars at the corner of the rigid-frame structure. Both experiments and numerical analyses were performed. Prototype models were constructed and subjected to static loading tests to reveal their load-carrying capacity and failure mode. Numerical models were then developed using finite elements to evaluate the experimental results. Analyses elicited good agreement between simulation and experimental data and validated the numerical models. Moreover, the validity of the proposed rigid connection was confirmed, and the failure behavior was clarified. Finally, a full-size model of the reinforced concrete rigid-frame bridge with H-shaped steel girders was constructed and subjected to destructive loading tests to evaluate structural integrity of the proposed rigid connection.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3A
• /
• pp.341-347
• /
• 2008

Among coating systems used for steel bridge coatings on highway such as red lead-pigmented alkyd, chlorinated rubber, waterborne inorganic zinc, inorganic zinc/epoxy/urethane and inorganic zinc/epoxy/fluororesin, evaluation of deterioration degree and prediction of lifetime through regression analysis were carried out for coating systems widely used and grossly degraded. For evaluation of deterioration degree, 75 bridges on highway were selected, and evaluations were carried out according to point offering method regulated by Guideline of maintenance coating for steel bridges used in Korea Expressway Corporation. Lifetime prediction results showed 13.0~13.3 years for the whole nation, 11.8 years for urban and industrial region in the metropolitan area, 13.2 years for rural region except the metropolitan area, 13.5~13.7 years for chlorinated rubber coating systems, and 12.86 years for red lead-pigmented alkyd systems. For prediction of the rest life of coating, we tried to execute parallel translations of standard deterioration curve to current life and deterioration degree for both x and y axes, and it was thought that parallel translation for x axis corresponded to deterioration aspects in actual environment. Maximum and minimum equations were derived from standard deterioration equation by adding and subtracting error values deduced in regression analysis to/from each coefficient in order to establish maintenance coating criteria for overall steel bridges on highway. Whole domain was divided into 8 parts in order to predict the rest life of coating and optimum time of maintenance coating, and maintenance coating criteria for each 8 domains were presented.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6A
• /
• pp.977-988
• /
• 2006

The goal of this study is to develop a realistic methodology for determination of the Life-Cycle Cost (LCC)-effective optimal seismic retrofit and maintenance strategy of deteriorating bridges. The proposed methodology is based on the concept of minimum LCC which is expressed as the sum of present value of seismic retrofit costs, expected maintenance costs, and expected economic losses with the constraints such as design requirements and acceptable risk of death. The proposed methodology is applied to the LCC-effective optimal seismic retrofit and maintenance strategy of a steel bridge considered as a example bridge in the accompanying study, and various conditions such as corrosion environments and Average Daily Traffic Volumes (ADTVs) are considered to investigate the effects on total expected LCC. In addition, to verify the validity of the developed methodology, the results are compared with the existing methodology. From the numerical investigation, it may be positively expected that the proposed methodology can be effectively utilized as a practical tool for the decision-making of LCC-effective optimal seismic retrofit and maintenance strategy of deteriorating bridges.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.6
• /
• pp.1-11
• /
• 2021

As the aging of large domestic SOC facilities accelerates, facility maintenance is also changing from safety evaluation based on the current condition to performance-oriented preventive and preemptive maintenance based on the prediction of the level of future obsolescence. In particular, in the case of bridges, class 1 and 2 bridges are systematically managed along with many studies, but for small and medium-sized class 3 bridges there is no collection and utilization of historical data presenting performance degradation during their service life. Therefore, in this study, 3D model-based demonstration DB system was designed and developed to intuitively check the damage change rate at the damage location by registering the maintenance history by life cycle for each member's exterior damage in the 3D bridge object and to enable API-based comprehensive performance evaluation.

• Journal of Korean Society of Disaster and Security
• /
• v.9 no.1
• /
• pp.33-38
• /
• 2016

Real time location system was development for safety management at road and bridge maintenance field. The system can check the real-time location detection, movement history, behavior of a number of laborers. The system consisted of a Bluetooth and ZigBee that uses low-power. It had a very large error that the previous method for the position recognition by triangulation using the RSSI. Because This study proposed a new distance measurement and correction scheme using RSSI and accelerometer. It was evaluated in the maintenance field. A development system were evaluated in the field, the results are shown an error between 0.2 m and 0.4 m. And through the acceleration of history it was confirmed by determining possible to determine the safety situation of the laborers.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.33 no.1
• /
• pp.55-61
• /
• 2020

Social infrastructure facilities that have been under construction since the country's high-growth period are undergoing rapid aging, and, thus, safety assessments of large structures such as bridge tunnels, which can be directly linked to large-scale casualties in the event of an accident, are necessary. It is difficult to construct economical and efficient wireless smart sensor networks that improve structural health monitoring (SHM) because the existing wire sensors have a short signal reach. However, low-power wide-area networks (LPWANs) are becoming popular within the Internet of Things, and enable economical and efficient SHM. In this study, the technology trends of a wireless measuring sensor based on LoRa LPWANs were investigated, and an installation and maintenance plan for this type of sensor is proposed.