On the applicability of the 1D inverse FEM to long-span bridges with applications to shape sensing and damage detection

This article presents an advancement in structural health monitoring (SHM) for long-span suspension bridges based on the inverse finite element method (iFEM). The approach is applied to a 1:250-scale three-span suspension bridge model and enables both shape sensing and damage detection through the reconstruction of structural response from strain measurements, without requiring prior knowledge of external loads. The experiments involved both static and dynamic loading conditions, including moving loads traveling along the deck to simulate realistic service scenarios. Strain measurements were acquired using fiber Bragg grating optical sensors installed along the central span of the bridge. The reconstructed displacements were validated against independent measurements obtained from laser displacement sensors, demonstrating the accuracy of the proposed computational approach. In addition, the proposed framework enables damage detection and localization through the integration of an anomaly index coupled with iFEM, with particular focus on scenarios involving complete loss of tension in selected hangers of the central span. Overall, the proposed methodology represents a significant advancement in load-independent SHM of suspension bridges, enabling real-time assessment and showing strong potential for application to full-scale structures under operational conditions.