Revealing fundamental flexural behavior of reinforced concrete slabs using distributed fiber optic sensors

Distributed fiber optic sensors (DFOS) allow for the measurement of distributed strains on concrete surfaces and along steel reinforcement in reinforced concrete (RC) members, and these measurements can quantify reinforcement and concrete behavior. In this investigation, concrete surface and reinforcement strains from DFOS were used to quantify and compare the structural behavior of lightly and moderately reinforced one‐way slabs strips to better characterize localized strain behavior of lightly reinforced RC members with small diameter bars (10 M). By quantifying the entire compression region and reinforcement strain behavior, various structural parameters, such as curvature, strain profiles over the height at various locations, and neutral axis depth were calculated. From the distributed properties, it was determined that significant differences in behavior existed between moderately and lightly reinforced specimens with small diameter bars, with the lightly reinforced specimen displaying non‐uniform behavior along its length. Differences observed in the lightly reinforced member with small diameter bars include local curvature differences both at a crack and between cracks, local evidence of plane sections not remaining plane, possible different internal cracking mechanisms, amongst other local strain behavior differences, which could have implications for future modeling and design of lightly reinforced RC members with small diameter bars.