PSI - Issue 75

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

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 75 (2025) 546–554

© 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 the responsibility of Dr Fabien Lefebvre with at least 2 reviewers per paper Abstract Tubular joints are common in offshore structures, among others for foundations for wind energy convertors. In the JaCo project, large-scale tests were performed in-plane and out-of-plane on 45° joints. A consistent different cracking behaviour was observed between joints loaded in-plane compared to joints loaded out-of-plane. The in-plane loaded joints fail by cracking through the brace, after crack initiation at the crown heel and a limited crack growth in the width. The stiffness of the joint is also almost constant until failure. Cracks initiate at the saddle points in out-of-plane loaded joints and propagate along the weld toes, reaching a very large width. A significant decrease of the joint stiffness is observed at failure, allowing for a redistribution of the load during the test. Although the fatigue life in design rules is described by the same S-N curve, it was found that the fatigue life for in-plane loading is shorter than for out-of-plane loading, highlighting a limitation of the current hot spot method. © 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 Fatigue Design 2025 organizers Keywords: Tubular Joints; Fatigue, welds; Steel, Offshore; 1. Introduction Offshore wind energy has emerged as a promising renewable resource, contributing significantly to global energy production. The future development of this energy source needs constant improvement to achieve the goal of affordable renewable energy. In particular, the foundations of offshore wind energy converters (WEC) are steel Fatigue Design 2025 (FatDes 2025) Results of the Jaco project: Effect of in-plane and out-of-plane loading on the cracking behaviour of tubular joints during large scale tests Philippe Thibaux a *, Jeroen Van Wittenberghe a a :OCAS NV, Kennedylaan 3 9060 Zelzate Belgium

* Corresponding author. Tel.: +32 474 55 84 50 E-mail address: Philippe.thibaux@ocas.technology

2452-3216 © 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 Fatigue Design 2025 organizers

2452-3216 © 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 the responsibility of Dr Fabien Lefebvre with at least 2 reviewers per paper 10.1016/j.prostr.2025.11.055