Measurement and visualization of strains and cracks in CFRP post-tensioned fiber reinforced concrete beams using distributed fiber optic sensors

This paper presents a method to measure and visualize strains and cracks in high-performance fiber-reinforced concrete using distributed fiber optic sensors based on optical frequency domain reflectometry. Two beams were prepared using high-performance concrete with two types of fibers and post-tensioned with carbon-fiber reinforced polymer (CFRP) tendons. The beams were instrumented with distributed sensors which were installed using two methods compatible with realistic construction. The beams were tested under four-point bending until failure. The distributed sensors measured strain distributions over the length of the beams in real time. The strain distributions are analyzed to detect, locate, trace, quantify, and visualize cracks during the processes of their initiation and propagation. The crack widths measured from the distributed sensors as well as a crack microscope are in a good agreement. This study is expected to promote distributed sensing technology for monitoring and control of construction and operation automation in new and existing structures.