These steel cables on suspension bridges and cable-stayed bridges are major members that transmit the dead and live load through the bridge’s main cable; hence, it is essential that inspection, maintenance and reinforcement are done regularly. In this study, we developed a magnetic sensor which is capable of detecting possible internal damages on bridge cables. It can be utilized to monitor actual suspension bridges and cable-stayed bridges.

Maintenance of plant facilities are becoming important due to lots of recent plant construction. While maintenance of plant facilities are performed, maintenance of plant structures are usually not carried out properly. In this paper, measurement threshold estimation algorithm is developed for maintenance of pipe-rack structure. Currently, field verification of the developed algorithm is being performed on a real pipe-rack structure.

Recently, Maintenance and inspection of plant are now being actively studied with the development of plant industry. In this paper, A leak detection in piping facilities using thermal imaging camera is proposed. This method was verified by laboratory experiment. In future, Appropriate algorithm will be applied to this method for real time detection and finally applied to the plant that is the ultimate goal of this study.

In this study, an automated cable non-destructive test (NDT) system was proposed to monitor the steel cable. Magnetic Flux Leakage (MFL) method was applied for the cable inspection. A multi-channel MFL sensor head was fabricated using Hall sensors and permanent magnets. A wheel based Cable climbing robot was used to improve the accessibility to cable. In addition, remote data transmission and robot control were possible by applying the Wireless LAN communication. Finally, developed element techniques were integrated to MFL based Cable Climbing NDT system, and the field applicability of the integrated cable NDT system was verified through a field test.

The limit state design code for reliability-based design criteria was enacted in January 2012. And, it was necessary to consider new load carrying capacity method for new design code. Therefore, LRFR and ballowable stress design rating was applied to load carrying capacity and compared with the result. In addition, this research consists of ambient vibration measurement, experimental modal analysis, correction of the initial FE model based on the identified modal properties, and estimation of the load carrying capacity using the updated FE model

This study introduces an efficient image-based three-dimension motion tracking system for civil structures. The proposed system consists of hardware (four camcorders, a commercial PC and frame grabber) and software. The effective software and measurement scheme are developed to obtain the dynamic motion with six degrees of freedom. Several laboratory tests were conducted to verify the effectiveness of the proposed system with the maximum error of less than 3%.

Steel cables are frequently used for various infrastructures. Especially the steel cables in long span bridges are critical members Damage at cable members can occur in the form of cross sectional loss caused by corrosion and fracture. Therefore, NDE of steel cable is needed to measure the cross-sectional damage. In this study, Total Magnetic Flux sensor system was applied to monitor the condition of cables. This system measures total magnetic flux to detect the loss of metallic cross section area(LMA) of steel cable. To verify the feasibility of this study, 2 types of steel bar were fabricated and their output values measured by the search coil in total flux sensor.

In this study, an MFL(Magnetic Flux Leakage)-based NDT(non-destructive test) method was applied to detect the inner damages of steel cable. A steel cable bunch specimen with several types of inner damage was fabricated and scanned by a MFL sensor head to measure the magnetic flux density of the specimen.the measured magnetic flux signal was visualized into a 3D MFL image for convenient cable monitoring. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the proposed cable monitoring method.

Since cable members are the major structural components in cable bridges, they should be properly inspected for surface damage as well as inside defects such as corrosion and/or breakage of wires. In this study, only the vision-based surface damage detection system based on image processing techniques is addressed. The damage detection programs are consist of real-time and post processing detection programs. The proposed damage detection programs were verified through laboratory tests on many types of cables.

Conventionally, the load carrying capacities of bridges have been evaluated from proof loading tests with test trucks by measuring static and dynamic response, such ad deflections or strains under known loading conditions. However, load carrying capacity of bridges was evaluated using the updated finite element (FE) model. To solve these problems, deflections or strains can not represent the bridge's health status as the bridge gets deteriorated. For example, deteriorated boundary condition results in small deflection or strain. The proposed method consists of ambient vibration measurement, experimental modal analysis, correction of the initial FE model based on the identified modal properties, and estimation of the load carrying capacity using the updated FE model. The proposed method has been verified through field tests on a prestressed concrete girder bridge by comparing with the result of the conventional truck loading tests.

In this paper, a research was performed to estimate dynamic characteristics of bridges using wireless sensors. First, the developed wireless sensors were compared with wired sensors through laboratory tests. Field tests were carried out on a steel box girder bridge. Dynamic characteristics of the test bridge were identified from the measured data by wireless sensors. As a result, it was proven that the wireless sensor system could be effectively applied to the measurement of large civil-infra structures.

This study introduces an algorithm for geometric distortion corrections in sonar images. The proposed algorithm mainly consists of two stages. At the first stage, the raw images are processed with median filter and Frost filter for noise reduction and intensity enhancement. In the last stage, the geometric distortion correction is conducted using angular information given by a gyro sensor. The algorithm was successfully applied on raw sonar data collected on a pier survey.

Damages due to typhoon and floods are increasing as a result of global warming and abnormal climate phenomenon over the world. Flood and scour is one of the major causes for bridge collapse. However, maintenance and inspection techniques still need improvements especially for underwater structures like bridge piers in rivers. Conventionally, manual inspection by divers has been carried out for underwater structures of bridges. This has difficulties in gathering accurate and reliable field data under severe environmental conditions. Therefore, in this study, underwater inspection of bridges has been carried out using the side scan sonar (SSS), one of unmanned underwater inspection equipment. Compared to the conventional manual inspection, it has been found that the SSS can be efficiently utilized to underwater inspection of bridges especially with bad visibility or large-scale inspection area.