PSI - Issue 64

Henrik Becks et al. / Procedia Structural Integrity 64 (2024) 1279–1286 Henrik Becks / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Conclusions and outlook In summary, the preliminary experiments presented demonstrate that the developed FOS system (combination of application method, adhesive, and fiber type) is capable of high-resolution monitoring of surface strain in plain and reinforced concrete under monotonic and fatigue loading. This applies both before crack formation, when the strain is below 100 μm/m, and after crack formation, when reinforcement is already yielding, and strain peaks of 14,000 μm/m are reached. The only challenge thus far has been excessively large strain gradients, which are not correctly captured by the utilized measurement technique. The performance of FOS compared to other strain measurement systems (e.g., DIC) and the influence of crack formation on measurement quality are currently being investigated in a large-scale experimental campaign. Furthermore, an evaluation tool has already been programmed in Python, which can read, process, and output two dimensional strain profiles based on an externally applied measuring fiber network (2D-FOS). The first results of these studies have been summarized and discussed in two comprehensive journal papers, which are currently under review. Acknowledgements The authors gratefully acknowledge the support for this research by the Deutsche Forschungsgemeinschaft (DFG) within the scope of the Priority Program SPP2388 "100+" (Project number: 501771082). References Becks, H., Baktheer, A., Marx, S., Classen, M., Hegger, J. & Chudoba, R. (2023). Monitoring concept for the propagation of compressive fatigue in externally prestressed concrete beams using digital image correlation and fiber optic sensors. Fatigue & Fracture of Engineering Materials & Structures , 46 (2), 514-526. https://doi.org/10.1111/ffe.13881 Becks, H., Bielak, J., Camps, B. & Hegger, J. (2022). Application of fiber optic measurement in textile-reinforced concrete testing. Structural Concrete , 23 (4), 2600-2614. https://doi.org/10.1002/suco.202100252 Becks, H., Brockmann, D., Hegger, J. & Classen, M. (2023). Monitoring the Fatigue ‐ Induced Strain Evolution of Concrete Bridges using Fiber Optic Sensors. ce/papers (EuroStruct 2023) , 6 (5), 1119 – 1126. https://doi.org/10.1002/cepa.2033 Becks, H. & Classen, M. (2024). New insights into the load sequence effect: Experimental characterization and incremental modeling of plain high-strength concrete under mode II fatigue loading with variable amplitude. International Journal of Fatigue , 185 , 108334. https://doi.org/10.1016/j.ijfatigue.2024.108334 Berrocal, C. G., Fernandez, I. & Rempling, R. (2021). Crack monitoring in reinforced concrete beams by distributed optical fiber sensors. Structure and Infrastructure Engineering , 17 (1), 124 – 139. https://doi.org/10.1080/15732479.2020.1731558 Blasón, S., Poveda, E., Ruiz, G [G.], Cifuentes, H. & Fernández Canteli, A. (2019). Twofold normalization of the cyclic creep curve of plain and steel-fiber reinforced concrete and its application to predict fatigue failure. International Journal of Fatigue , 120 , 215 – 227. https://doi.org/10.1016/j.ijfatigue.2018.11.021 Herbers, M., Richter, B., Gebauer, D., Classen, M. & Marx, S. (2023). Crack monitoring on concrete structures: Comparison of various distributed fiber optic sensors with digital image correlation method. Structural Concrete , Artikel suco.202300062. Vorab Onlinepublikation. https://doi.org/10.1002/suco.202300062 Janiak, T., Becks, H., Camps, B., Classen, M. & Hegger, J. (2023). Evaluation of distributed fibre optic sensors in structural concrete. Materials and Structures , 56 (159). https://doi.org/10.1617/s11527-023-02222-9 Oneschkow, N. (2016). Fatigue behaviour of high-strength concrete with respect to strain and stiffness. International Journal of Fatigue , 87 , 38 – 49. https://doi.org/10.1016/j.ijfatigue.2016.01.008 Ortega, J. J., Ruiz, G [Gonzalo], Poveda, E., González, D. C., Tarifa, M. A., Zhang, X., Yu, R. C., Vicente, M. Á., La Rosa, Á. de & Garijo, L. (2022). Size effect on the compressive fatigue of fibre-reinforced concrete. Construction and Building Materials , 322 , 126238. https://doi.org/10.1016/j.conbuildmat.2021.126238 Richter, B., Herbers, M. & Marx, S. (2023). Crack monitoring on concrete structures with distributed fiber optic sensors — Toward automated data evaluation and assessment. Structural Concrete , 25 (2), 1465 – 1480. https://doi.org/10.1002/suco.202300100