Measuring support reactions and damage detection in steel beams using distributed strain sensing

While visual inspections are an important tool in the assessment of steel bridges, they cannot provide quantitative information about the bridge's behavior. Distributed fiber optic sensors (DFOS) have the potential to provide added insight into the performance of bridges through the measurement of full strain profiles along a member as well as other key performance indicators that can be derived from these measurements. This study investigates the use of DFOS measurements to derive support reactions and detect local damage along the flexural members in a bridge. A series of load tests were undertaken to develop the method for support reaction estimation, starting with a simply supported beam, then continuous beams, and then finally a full model bridge. The beam test support reactions were evaluated against load cell measurements and variations in geometry were shown to have an impact on the measurements that could be accounted for through calibration. The model bridge reactions matched the total applied load and showed the expected distribution for the loading configuration applied. A second model bridge test was undertaken where the shear stress in the connection between the beams and the slab exceeded the capacity of the connection and localized damage occurred. Using the DFOS measurements, the neutral axis was calculated and used to detect this localized damage.

Automated summary

This study utilizes distributed fiber optic sensors (DFOS) measurements to derive support reactions and detect local damage on flexural members of a bridge. Through a series of load tests, it is demonstrated that DFOS measurements play a crucial role in assessing bridge performance and adjustments for geometry variations can be made through calibration.