PSI - Issue 62

Silvia Caprili et al. / Procedia Structural Integrity 62 (2024) 355–360 Caprili et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 6. Numerical calibration result.

4. Conclusions Preliminary results on a wide experimental campaign executed on strands subjected to natural corrosion environment causing hydrogen embrittlement (HE) phenomenon are presented. The strands were exposed, for different months, to the action of air and water coming from the injection nozzles, not opportunely protected before grouting injection; strands were already in tension (about the 60% of the ultimate strength), and therefore the corrosion process was accelerated. A sudden modification of the mechanical characteristics, mainly in terms of deformation capacity associated to a resulting wire-by-wire failure modality of corroded strands was appreciated even in presence, as revealed by the X-ray tomographies, of small pit (in terms of depth, length and width).What herein shortly described is coherent with the corrosion HE mechanisms detected in the analysed strands, where even small entity of corrosion pits is enough to activate corrosion, further propagating and leading to sudden drops of ductility due to the progressive brittle failure of single wires. Preliminary results of detailed 3D FEM analyses on corroded strands have been also shown, with the aim to calibrate results of experimental tests as base to elaborate predictive models of the residual capacity of strands in corroded Li, F., Yuan, Y. and Li, C.Q., 2011. Corrosion propagation of prestressing steel strands in concrete subject to chloride attack. Construction and Building Materials, 25(10), pp.3878-3885. Nürnberger, U., 2002. Corrosion induced failure mechanisms of prestressing steel. Materials and Corrosion, 53(8), pp.591-601. Sason, A.S., 1992. Evaluation of degree of rusting on prestressed concrete strand. PCI Journal, 37(3), pp.25-30. EN ISO 15630- 3:2019 ‘Steel for the reinforcement and prestressing of concrete’. D.M.17/01/2018 ‘Italian standard for Construction’(in Italian). EN 10218- 1:2012 ‘Steel wire and wire products - General - Part 1: Test methods’. SIST ISO 7801:1996 ‘Metallic materials - Wire - Reverse bend test’. Franceschini, L., Vecchi, F., Tondolo, F., Belletti, B. and Montero, J.S., 2022. Mechanical behaviour of corroded strands under chloride attack: A new constitutive law. Construction and Building Materials, 316, p.125872. Franceschini, L., Belletti, B., Tondolo, F. and Sanchez Montero, J., 2023. A simplified stress – strain relationship for the mechanical behavior of corroded prestressing strands: The SCPS‐model. Structural Concrete, 24(1), pp.189-210. Jeon, C. H., Lee, J. B., Lon, S., & Shim, C. S. (2019). Equivalent material model of corroded prestressing steel strand. Journal of Materials Research and Technology, 8(2), 2450-2460. Wang, L., Li, T., Dai, L., Chen, W. and Huang, K., 2020. Corrosion morphology and mechanical behavior of corroded prestressing strands. Journal of Advanced Concrete Technology, 18(10), pp.545-557. Abaqus, G., 2011. Abaqus 6.11. Dassault Systemes Simulia Corporation, Providence, RI, USA, 3. conditions. References