Carbon fiber sheet surface adhesion method is a well-known repair and reinforcement method for concrete structures like bridges and buildings. The method has high tensile strength and durability. However, the attached sheet is easy to detached from the structure during and after the construction because of the method’s labor intensive characteristics. An accurate measurement and evaluation system of damage location needed to identify the type of damages. In this study, a conceptual design of fiber optic sensor embedded carbon fiber sheet was developed to track the measured signal by deflection of the samples using BOTDR. After the analysis of the measured value, it verifies the applicability of the optical fiber embedded carbon fiber sheet to check the state of a reinforced structure.
The method of reinforcing the structure by attaching the carbon fiber sheet started from the mid 1980's in EMPA in Switzerland. The research has been utilized in reinforcing many structures from 1990. The carbon fiber sheet adhesion reinforcing method is often difficult to completely adhere due to various reasons, and may fall off or peel off with the lapse of time. When reinforcement performance of a structure strengthened with a carbon fiber sheet decreases due to peeling of adhesion. Survey of many damage cases and theoretical study on the effect of detachment or peeling of carbon fiber sheet to the performance of the structure are needed to provide concrete solutions. This study analyzed the relationship between the separation of carbon fiber sheet and the performance of structures reinforced by carbon fiber sheet attachment method.
KEYWORDS: Inspection, Video, Image processing, Optical character recognition, Reliability, Image enhancement, Digital image processing, Video processing, Image analysis, Standards development
Recent frequent occurrence of urban sinkhole serves as a momentum of the periodic inspection of sewer pipelines. Sewer inspection using a CCTV device needs a lot of time and efforts. Many of previous studies which reduce the laborious tasks are mainly interested in the developments of image processing S/W and exploring H/W. And there has been no attempt to find meaningful information from the existing CCTV images stored by the sewer maintenance manager. This study adopts a cross-correlation based image processing method and extracts sewer inspection device’s location data from CCTV images. As a result of the analysis of location-time relation, it show strong correlation between device stand time and the sewer damages. In case of using this method to investigate sewer inspection CCTV images, it will save the investigator’s efforts and improve sewer maintenance efficiency and reliability.
This research introduces unfamiliarity index (UFI) that calculated from the FFT results of the short term timeline acceleration responses. If this algorithm, which can detect an abnormal behavior from the maximum constant signal, is used to the terminal sensors of a structure, more accurate safety control criteria will be prepared efficiently.
Damage to infrastructure is a real concern at present, caused primarily by worldwide climate anomalies, global warming, and natural disasters. Korea has begun research to develop a high precision patch/implant system using new IT techniques since 2011 and technologies which must be developed for this research are those which measure and evaluate the soundness and safety of structures based on the measurements of an attached sensor. During the research period since 2011, optical fiber sensor patches and wireless sensor capsule implants along with various sensor technologies, stress sensing and structural condition evaluation algorithm have been developed effectively for network hardware technologies as prototype version. Similarly high precision image processing for automatic crack extraction have been developed along with radiation sensor application technologies, combined management/control technologies for developed systems, and practical technologies for building and large scale structure. Through the results, it is expected that we acquire higher sensor system performance with a measurement scope (for precision, etc.) goal at least 200% better than conventional sensor systems.
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