Strain sensing and crack detection in prestressed concrete girders

Three 24 m long prestressed concrete girders were equipped with EpsilonRebars embedded inside. The sensors were delivered on-site in coils and tightened to the existing reinforcement. This fast and easy installation process allowed the creation of smart elements able to self-diagnose during all stages: concrete hardening, prestressing, mounting in the structure, as well as during the load tests. Currently, the girders are under continuous operation in one of Polish production halls.

DFOS Sensors Installed: EpsilonRebar

Project challenges

How to apply non-invasive diagnostics in demanding historic structures?
How to get precise measurement data to detect local damage and imperfection?
How to measure detailed strain profiles over the entire height of the brick masonry wall?

Benefits of using the DFOS monitoring system

Structural performance control during all construction stages and load tests
Detection of all the cracks formed during early-age concrete (hardening process)
Analysis of the effectiveness of prestressing process, including control of the cracks
Reliable system for short-term load tests and long-term structural monitoring

Results of using the DFOS monitoring system

The monitoring system created based on Nerve-Sensors provided unique data for structural analysis. The first stage (1) was concrete hardening when a number of microcracks were detected. However, all of them were closed (see the plots) during prestressing stage (and activation of dead weight at the same time), so girders could be installed on columns (2) without any risk. Finally, the structural performance was checked during mechanical load tests (3), which showed that the girders work in uncracked conditions. This knowledge was extremely valuable for designers and could be successfully used, e.g. for optimisation.

Technical specifications

57 600 measurement points
576 m of sensing path
24 x EpsilonRebar
short & long-term

Example results

Recomendations (optional)

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John Doe

Project partner

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