PSI - Issue 77

ScienceDirect Structural Integrity Procedia 00 (2025) 000 – 000 Structural Integrity Procedia 00 (2025) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect

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

Procedia Structural Integrity 77 (2026) 339–347

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 2025 organizers 1. Introduction The distinct configurations of specimens used in fracture mechanics to measure the toughness of metallic materials in an inert environment have much in common, but as revealed by Valiente et al. (2016) and by Iordachescu and Perez-Guerrero (2018) , in the case of some structural steels, key in civil engineering, none of these configurations are adapted to the geometry of the final 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 2025 organizers 1. Introduction The distinct configurations of specimens used in fracture mechanics to measure the toughness of metallic materials in an inert environment have much in common, but as revealed by Valiente et al. (2016) and by Iordachescu and Perez-Guerrero (2018) , in the case of some structural steels, key in civil engineering, none of these configurations are adapted to the geometry of the final International Conference on Structural Integrity On cohesive fracture behaviour of ultrahigh-strength lath martensitic tendon-rods for structural engineering P. Santos a,b* , A. Valiente a , M. De Abreu a , M. Iordachescu a a Material Science Dpt., ETSI Caminos, Polytechnic University of Madrid, 5 Prof. Aranguren St., 28040-Madrid, Spain b Applied Physics and Materials Engineering Dpt., ETSI Industriales, Polytechnic University of Madrid, 2 José Gutiérrez Abascal St., 28006 Madrid, Spain Abstract The work examines the fracture behaviour of a lath-martensitic steel, recently employed to manufacture ultrahigh-strength tendon-bars for structural engineering. In this view, the steel was fracture tested by using fatigue pre-cracked SENT specimens and assessed on the experimental and theoretical bases respectively provided by the BS- 8571 standard and Dugdale’ s cohesive model. The assessment relays on the comparison of the load and J-integral versus CMOD curves resulting from the fracture tests and from the predictions of the cohesive model applied to the SENT specimen configuration on the basis of the Green function proposed by Chell, the superposition principle and the Maxwell-Betty reciprocal theorem for Hookean cracked bodies. It was found that the J-integral linearly increases with CMOD once the small-scale regime vanishes, whereas the loading process becomes asymptotically unstable. The corresponding slope and maximum load are a function of the crack size and the cohesive resistance. The comparison shows that the cohesive crack accurately models the mechanism by which the steel opposes to crack propagation when mechanically loaded and allows the cohesive resistance of the steel to be obtained from the experimental slopes and maximum loads. The values obtained are fully consistent with the condition of being a material constant and with the physical meaning attributed to it by the cohesive model. © 2025 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 2025 organizers Keywords: ultra-high strength martensitic steel; cohesive fracture model; SENT specimen International Conference on Structural Integrity On cohesive fracture behaviour of ultrahigh-strength lath martensitic tendon-rods for structural engineering P. Santos a,b* , A. Valiente a , M. De Abreu a , M. Iordachescu a a Material Science Dpt., ETSI Caminos, Polytechnic University of Madrid, 5 Prof. Aranguren St., 28040-Madrid, Spain b Applied Physics and Materials Engineering Dpt., ETSI Industriales, Polytechnic University of Madrid, 2 José Gutiérrez Abascal St., 28006 Madrid, Spain Abstract The work examines the fracture behaviour of a lath-martensitic steel, recently employed to manufacture ultrahigh-strength tendon-bars for structural engineering. In this view, the steel was fracture tested by using fatigue pre-cracked SENT specimens and assessed on the experimental and theoretical bases respectively provided by the BS- 8571 standard and Dugdale’ s cohesive model. The assessment relays on the comparison of the load and J-integral versus CMOD curves resulting from the fracture tests and from the predictions of the cohesive model applied to the SENT specimen configuration on the basis of the Green function proposed by Chell, the superposition principle and the Maxwell-Betty reciprocal theorem for Hookean cracked bodies. It was found that the J-integral linearly increases with CMOD once the small-scale regime vanishes, whereas the loading process becomes asymptotically unstable. The corresponding slope and maximum load are a function of the crack size and the cohesive resistance. The comparison shows that the cohesive crack accurately models the mechanism by which the steel opposes to crack propagation when mechanically loaded and allows the cohesive resistance of the steel to be obtained from the experimental slopes and maximum loads. The values obtained are fully consistent with the condition of being a material constant and with the physical meaning attributed to it by the cohesive model. © 2025 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 2025 organizers Keywords: ultra-high strength martensitic steel; cohesive fracture model; SENT specimen © 2026 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 ICSI organizers

2452-3216 © 2026 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 ICSI organizers 10.1016/j.prostr.2026.01.044