Equivalent estimation method (EEM) for quasi-distributed bridge-deflection measurement using only strain data

Deflection is a crucial parameter for bridge health monitoring procedures. In this paper, an equivalent estimation method (EEM) is proposed for quasi-distributed deflection estimation using onboard strain data. Leveraging the installation of the self-designed sensing bar on the bridge girder, an equivalent analysis model is established. An innovative inverse finite element method (iFEM) is employed to discretize the model and to establish a straindeflection transformation matrix. Then, quasi-distributed bridge deflections are estimated by reconstructing the deformed shape of the equivalent analysis model. The present model is simple and independent of the typology of bridge structures, making the EEM sufficiently general to analyse complex bridges. The EEM framework is computationally fast, powerful, and robust for real-time applications since iFEM enables deformation predictions by simple matrix-vector multiplication without a priori loading and material information. Experimental validation cases have been performed, and they demonstrate the excellent quasi-distributed sensing capability of the EEM.