Structural health monitoring and digital twin-based diagnosis of a prestressed concrete bridge

This study develops a comprehensive Structural Health Monitoring (SHM) strategy applied to the Spyckstraße Bridge, a three-span composite slab-girder structure constructed in 1976, with the objective of evaluating its structural performance under current design standards and increased traffic loads. A short-term monitoring campaign based on non-destructive techniques was carried out to record dynamic responses, including vibrations, displacements, and modal properties. The collected data served to calibrate and validate a Digital Twin model through an iterative optimization process using a genetic algorithm, achieving a deviation below 3 % between experimental and numerical eigenfrequencies. Once validated, the Digital Twin was used to assess the structural response under code-compliant load combinations and to determine utilisation levels for all critical sections. The analysis showed that none of the structural components reached their ultimate limit state, although the maximum tensile utilisation (97.3 %) was identified in the external girder of the central span under combined extreme traffic and thermal loading conditions. Furthermore, a parametric study addressing tendon corrosion effects indicated notable variations in modal characteristics and a decrease in load-bearing capacity. These findings highlight the effectiveness of integrating short-term SHM data with calibrated numerical models as a reliable framework for structural assessment, enabling early damage detection, informed maintenance strategies, and enhanced lifecycle management of existing bridge assets.