Fiber optic sensing for bridge structural examination (SHM-DFOS)

Bridge assessment using high-resolution distributed fiber optic sensors for strain and temperature monitoring to evaluate structural performance.

The project at a glance

Start date:

01 Jun 2024
Duration in months:

36
Funding:

FNR
Principal Investigator(s):

Francesco FABBRICATORE

About

Existing concrete bridges, critical to transportation networks, are increasingly subjected to environmental and traffic stresses that can induce latent defects such as micro-cracks and corrosion. Traditional inspections often fail to detect these early-stage flaws, leaving structures vulnerable to unexpected deterioration. This study presents a structural performance monitoring methodology that combines high-resolution distributed fiber optic sensors (DFOS) with static load testing. DFOS provides continuous strain and temperature profiles, capturing global structural behavior and detecting localized effects often missed by conventional approaches. Applied to a full-scale prestressed concrete bridge in Switzerland, the method enabled accurate insight on the bridge structural response.

Figure 1: DFOS installation and strain signal output.

The methodology shows that DFOS generates comprehensive datasets, providing the detailed information required for thorough bridge assessment. Quasi-continuous measurements enable precise evaluation of bending moments, girder load distribution, boundary conditions and localized strain concentrations. This supports accurate displacement estimates and detailed crack detection, including complex interactions between the structural elements. Unlike traditional discrete-sensor methods, DFOS delivers spatially continuous data, capturing insights otherwise unattainable and giving engineers a more complete understanding of structural performance.

Figure 2: DFOS crack identification and deflection prediction.

Overall, the results confirm that DFOS-based monitoring is a powerful, data-driven tool for improving bridge safety, informing maintenance decisions, and supporting sustainable management of existing concrete girder bridges. By integrating advanced data collection, interpretation and structural understanding, this approach enhances the reliability of safety assessments and opens avenues for further research.