Damage/Deterioration Detection for Steel Structures Using Distributed Fiber Optic Strain Sensors

Distributed fiber optic sensors have the potential to be used to detect three critical deterioration mechanisms in steel structures: (1) fatigue cracking, (2) localized damage or deterioration, and (3) distributed damage or deterioration, such as corrosion. This study investigated the strain and spatial resolution of distributed fiber optic sensors and explored the potential benefits and challenges of using distributed fiber optic strain sensors for damage/deterioration detection. The experimental program consisted of a series of axial tension tests performed on steel plate specimens with three types of simulated damage/deterioration: cracking, local cross section reduction, and distributed cross section reduction. The results indicate that similar accuracy to strain gauges can be achieved and distributed fiber optic strain sensors can provide much more detailed information about specimen behavior. The results of a finite-element analysis for each specimen were compared with the experimental measurements. There was good correlation between the two if the boundary conditions were modeled properly. However, care must be taken when selecting the sensing fiber to be used and when interpreting the results.