Fiber optic strain monitoring of bridge column retrofitted with composite jacket under flexural loads

摘要

Abstract: This paper describes preliminary laboratory strain monitoring results of a 15-ft tall (2 ft in diameter) circular flexural lap- splice concrete column wrapped with a carbon-composite jacket. Optical fiber time domain (OFTD) strain sensors were embedded in the composite jacket in the hoop direction to monitor strains during testing. Optical fiber time domain methods are based on measuring the time-of-flight of optical signals launched into optical fibers which are embedded in or attached to flexible structures. This fiber-optic-based method allows in-line sensor multiplexing for distributed sensing along a single optical fiber strand. Time-domain multiplexing stands out as the most reliable and cost-effective approach to monitor strains within large civil structures over prolonged periods of time. In this study, the system utilizes novel fiber optic strain gauge patches. The strain values measured by the fiber optic strain gauge patches were compared to the values measured by conventional surface- mounted strain gauges. Excellent correlation between the fiber optic sensor data and the strain gauge data was obtained during the test. !4