Steel girders during mechanical load tests: elastic and plastic strains

A number of steel girders designed for bridge applications were investigated in laboratory conditions during mechanical tests. The research includes MCL girders as well as I- and H-beams. The challenge in this project was to measure extremely high strains, exceeding the range of elastic behaviour significantly. Thanks to DFOS strain sensors, it was possible to analyse the yielding process up to 20 000 µε in tension and 10 000 µε in compression.

DFOS Sensors Installed: Optical fibre in acrylate coating

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

Strain measurements during elastic and plastic behaviour of steel (20 000 µε)
Knowledge about residual strains, both in compression and tension zones
Thousands of measurement points over freely shape traces
Unique data for scientific analysis, FEM calibration and PhD thesis

Results of using the DFOS monitoring system

One of the research goals was to monitor the yielding process of steel girders, both in their compression and tension zones. The network of DFOS strain sensors installed within the structural elements allowed us to obtain a comprehensive picture of strains for different load schemes and force values. The figure below shows the example result of strain distributions for selected girder. The red line corresponds to residual strains, which remained after tests were completed.

Technical specifications

28 800 measurement points
288 m of sensing path
26 x strain sensors
short-term (load tests)

Example results

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John Doe

Project partner

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