Reference-free distributed monitoring of deflections in multi-span bridges
Dario Poloni, Maurizio Morgese, Chengwei Wang, Todd Taylor, Marco Giglio, Farhad Ansari, Claudio Sbarufatti
Abstract
The research presented herein pertains to developing a reference-free technique for monitoring bridge deflections under operational conditions. The method is based on monitoring the distributed strains along the length of bridges and employing the Inverse Finite Element Method (iFEM) to compute the deflection for the entire length of bridges. Distributed sensing of strains was achieved by a Brillouin Optical Time Domain Analysis system (BOTDA). The dynamic strains were then used in the iFEM algorithm to calculate the deflections of the structure. This approach computes structural displacements by a variational principle with minimal computational cost. Because of its independence from loads and material properties, the proposed methodology monitors the dynamic deflections during bridge routine traffic operations, and it is potentially viable for real-time monitoring. The approach is validated through two comprehensive case studies, including a laboratory experiment and a field application on a multi-span concrete bridge. • The developed method allows for estimating bridge deflection without fixed measurement references. • The approach combines iFEM and BOTDA sensors for reference-free deflection monitoring. • The proposed method can monitor the distributed deflections under static and dynamic operational conditions of the bridges. • The proposed approach is independent of the loading conditions and of the material properties of the structure. • The computational approach based on iFEM and the experimental and field evaluations are detailed in the article.