PSI - Issue 54

ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000 Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 54 (2024) 143–148

© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers Abstract The paper addresses the damage analysis of the prestressing steel strands of an urban viaduct opened to traffic in 1970. The viaduct, a post-tensioned reinforced concrete structure, has undergone over the last three decades an increasing tendency to cracking despite the repairs undertaken. In the latest inspection, the concrete cracking revealed the deterioration of the protective steel-sheaths of the prestressing steel strands with a significant level of damage. The research presented in this paper describes the scope and root causes of damage which, in some cases, induced the rupture of the strands. The analysis is based on the microstructural characterization of the steel, the tensile tests of samples in as-received condition and the comparative fractographic analysis of the fracture surfaces of in-service broken wires and laboratory-tested ones. It was found that neither the lack of quality nor the degradation of the steel caused the strand failures, but the concurrence of construction deficiencies and accidental environmental actions throughout 50 years of service. © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers Keywords: Fracture; Damage tolerance; Damage mechanisms; 1. Introduction The paper addresses the damage analysis of the prestressing steel strands of an urban viaduct opened to traffic in 1970. The viaduct, a post-tensioned reinforced concrete structure, has been prone over the last three decades to an increasing tendency to cracking despite the repairs undertaken. The latest inspection allowed the protective steel sheaths of prestressing steel wire-strands to be accessed and revealed the deterioration of the located ones in the central spans of the viaduct, with failed strands and absence of cement-grout injection (Fig. 1a). In this view, the research explores the possible causes of the deterioration state and the detected failures of the steel wire-strands. The analysis is based on the microstructural and tensile characterization of the prestressing steel after 50 years in service, as well as on the comparative fractographic analysis of the service fracture surfaces with 2452-3216 © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers International Conference on Structural Integrity 2023 (ICSI 2023) Damage analysis of the prestressing strand-wires from a 50-year-old urban viaduct Maricely De Abreu a *, Mihaela Iordachescu a , Andrés Valiente a a Material Science Dpt., ETSI Caminos, Universidad Politécnica de Madrid, 5 Prof. Aranguren St., 28040-Madrid, Spain Abstract The paper addresses the damage analysis of the prestressing steel strands of an urban viaduct opened to traffic in 1970. The viaduct, a post-tensioned reinforced concrete structure, has undergone over the last three decades an increasing tendency to cracking despite the repairs undertaken. In the latest inspection, the concrete cracking revealed the deterioration of the protective steel-sheaths of the prestressing steel strands with a significant level of damage. The research presented in this paper describes the scope and root causes of damage which, in some cases, induced the rupture of the strands. The analysis is based on the microstructural characterization of the steel, the tensile tests of samples in as-received condition and the comparative fractographic analysis of the fracture surfaces of in-service broken wires and laboratory-tested ones. It was found that neither the lack of quality nor the degradation of the steel caused the strand failures, but the concurrence of construction deficiencies and accidental environmental actions throughout 50 years of service. © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers Keywords: Fracture; Damage tolerance; Damage mechanisms; 1. Introduction The paper addresses the damage analysis of the prestressing steel strands of an urban viaduct opened to traffic in 1970. The viaduct, a post-tensioned reinforced concrete structure, has been prone over the last three decades to an increasing tendency to cracking despite the repairs undertaken. The latest inspection allowed the protective steel sheaths of prestressing steel wire-strands to be accessed and revealed the deterioration of the located ones in the central spans of the viaduct, with failed strands and absence of cement-grout injection (Fig. 1a). In this view, the research explores the possible causes of the deterioration state and the detected failures of the steel wire-strands. The analysis is based on the microstructural and tensile characterization of the prestressing steel after 50 years in service, as well as on the comparative fractographic analysis of the service fracture surfaces with 2452-3216 © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers International Conference on Structural Integrity 2023 (ICSI 2023) Damage analysis of the prestressing strand-wires from a 50-year-old urban viaduct Maricely De Abreu a *, Mihaela Iordachescu a , Andrés Valiente a a Material Science Dpt., ETSI Caminos, Universidad Politécnica de Madrid, 5 Prof. Aranguren St., 28040-Madrid, Spain

2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers 10.1016/j.prostr.2024.01.066