Development and application of FBG retard-bonded smart steel strands

In this paper, in order to solve the defects of sensors and distributed process for monitoring the stress of retard-bonded steel strand, according to characteristics of retard-bonded prestressed concrete and optical fiber sensing, novel self-monitoring retard-bonded smart steel strand was designed and manufactured. Then the FBG retard-bonded smart steel strand were applied to a retard-bonded prestressed one-way slab in a Hall, and the availability and reliability of the novel smart steel strands was verified. The results show that the retard-bonded smart steel strands have simple structure and definite mechanism. The mechanical properties of the smart steel strand are lower than ones of ordinary steel strand, and the smart strand has the ultimate tensile strength of about 88% of common strand, and the sensing properties (hysteresis, repeatability, linearity, and total accuracy) are less than 3%. It has been verified that the novel smart steel strand have the advantages of simple and easy construction process by the application in the practical project. And the robustness of the novel smart strand can meet the long-term monitoring for prestress losses in the practical engineering.