PSI - Issue 64

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Maciej Kulpa et al. / Procedia Structural Integrity 64 (2024) 1673–1680 Kulpa / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 11. The natural frequency spectrum distribution obtained from the DFOS system

4. Conclusion The proof load tests confirmed the proper behaviour of the footbridge under static and dynamic loads. The FRP footbridge structure behaved elastically and the induced strains were well below the strength of the material. The compliance of the measured and calculated displacements and the first natural frequency for the spans was in the range of 93-98%, which validates the numerical model used for design. The first in situ application of the newly developed DFOS monitoring system was successful. The DFOS system showed high compliance with conventional measurements performed during the load-tests. This confirms the correct operation, accuracy and reliability of the new monitoring system. By placing a large number of sensors in one optical fibre along the entire length of the span - both in the upper and lower laminate - it was possible to accurately determine vertical displacements, even though they would not be measured directly. In the following years, static and dynamic tests are planned to be repeated periodically to compare the results and draw conclusions about the behaviour of the FRP composite structure over time, as well as about the durability of the DFOS monitoring system embedded in the composite structure. Acknowledgements This project was co-financed by the Minister of Science and Higher Education under the "Regional Excellence Initiative" program under contract no. RID/SP/0032/2024/01 entitled "Regional Center of Excellence in Engineering for Quality of Life and Technology Development ” . References Bakis, C. E., Bank, L. C., Brown, V., Cosenza, E., Davalos, J. F., Lesko, J. J., Machida, A., Rizkalla S. H., Triantafillou, T. C., 2002. Fiber reinforced polymer composites for construction—State - of - the - art review. Journal of composites for construction, 6(2), 73 - 87. De Corte, W., Jansseune, A., Van Paepegem, W., & Peeters, J. 2017. Structural behaviour and robustness assessment of an InfraCore inside bridge deck specimen subjected to static and dynamic local loading. In Proceedings of the 21st International Conference on Composite Materials, Xi’an (pp. 1 - 8). EuCIA - Prospect for New Guidance in the Design of FRP Structures (Eurocodes). European Composites Industry Association (EuCIA), Brussels, 2019 Kulpa, M., Howiacki, T., Wiater, A., Siwowski, T., & Sieńko, R. 2021. Strain and displacement measurement based on distribute d fibre optic sensing (DFOS) system integrated with FRP composite sandwich panel. Measurement 175: 109099. Manalo, A., Aravinthan, T., Fam, A., & Benmokrane, B. (2017). State - of - the - art review on FRP sandwich systems for lightweight civil infrastructure. Journal of Composites for Construction, 21(1), 04016068. Siwowski, T., Rajchel, M., Kaleta, D., & Własak, L. 2017. The first Polish road bridge made of FRP composites. Structural Engineering International 27(2): 308 - 314. Siwowski, T., Kulpa, M., & Rajchel, M. (2020). Advances in FRP composite vehicle bridges - the polish experience. Archives of Civil Engineering, 66(1).