Analysis of Strain Transfer Efficiency Coefficient of a Novel High-strength Steel Wire FBG Sensor

Accurately measuring cable forces is crucial for reliable bridge condition evaluation, yet it remains a challenging task. This study proposes the use of a High-strength Steel Wire Fiber Bragg Grating (HSW-FBG) sensor embedded in commonly-used cables composed of 5–7 mm parallel steel wires. The HSW-FBG sensor facilitates direct strain measurement, offering a simple and user-friendly packaging process for high-precision monitoring throughout the cable’s lifespan. The results demonstrate excellent linearity and repeatability in strain detection of the HSW-FBG sensor. The length of the packaging layer has the most significant impact on the strain transfer efficiency (STE) coefficient and should be at least 60 mm required for optimal performance. Additionally, the elastic modulus of the packaging layer moderately affects the STE coefficient. Adhering to these packaging parameter requirements ensures that the STE coefficient of the HSW-FBG sensor is very close to 1, enabling for high-precision measurement without correction. A systematic analysis of the STE coefficient of the HSW-FBG sensor is conducted, determining reasonable values for the packaging parameters. These findings lay the groundwork for future engineering applications, facilitating accurate measurement of cable forces in practical scenarios.