PSI - Issue 64

Maciej Kulpa et al. / Procedia Structural Integrity 64 (2024) 1339–1346 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4. The fiber optic sensors: arranging during panel production (on the left) and connected to intererogator unit (on the right)

A method of installing optical sensors directly on the composite material, developed and patented by the authors (Kulpa et al., 2021). Fibre optic sensors were placed in appropriate routes between dry fabrics in the mould (Fig. 4a). Then, after infusion of the fibres with resin in the VARTM process, the sensors became an integral part of the material. The sensors protrude beyond the prefabricated panel in a 3 mm thick sheath, and each of them is terminated with a plug for direct connection to the reflectometer (Fig. 4b). In each panel, sensors were installed in the outer laminates. In this way, approximately 60 meters of longitudinal measuring routes and approximately 12 meters of transverse measuring routes were created. As a result of VARTM processes during manufacturing, some of the sensors were damaged and approximately 75% of all installed sensors were able to perform measurements. This value was higher than in the original applications (Kulpa et al., 2021), but can be further increased to approximately 80-90%. The detailed location of the longitudinal measuring routes is shown in Fig. 5.

Fig. 5. The arrangement of longitudinal measurement routes in the upper (on the left) and lower (on the right) outer laminate

3. Proof load test 3.1. Load schemes

Before the reconstructed bridge was open to public use, a proof load test was carried out. It involved loading the span structure with six large tanks filled with water. The location of the tanks was arranged in two load schemes on two typical FRP panels: S1- the panel in the middle of the longest span, and S2 - the second panel from the bridge