Committee V.7: Structural Longevity
Authors: Lazakis Iraklis , Leira Bernt , Chen Nianzhong , Drumond Geovana , Lee Chi-Fang , Jurisic Paul , Liu Bin , Mondoro Alysson , Pahlavan Pooria , Shi Xinghua , Song Ha Cheol , Sugimura Tadashi , Jochum Christian , Coppola Tommaso 
Published: April 2023

Committee Mandate
Concern for the structural longevity of ship, offshore and other marine structures. This shall include diagnosis and prognosis of structural health, prevention of structural failures such as corrosion and fatigue, and structural rehabilitation. The focus shall be on methodologies translating monitoring data into operational and life-cycle management advice. The research and development in passive, latent and active systems including their sensors and actuators shall be addressed.

Introduction
1.1 Background & Mandate
The ISSC Committee V.7 on structural longevity of ship, offshore and other marine structures have been looking into all aspects related to the diagnosis and prognosis of structural health, prevention of structural failures such as corrosion and fatigue, while also considering the work performed on lifecycle management and maintenance aspects over the last 4 years. The latter refer to also incorporating approaches and techniques associated to the development of software and hardware tools for the inspection and monitoring of ship and offshore structures. In this Committee’s report, particular emphasis has been placed on the elaboration of the available studies and most recent developments with regards to inspection and monitoring and offshore structures longevity methods and applications, expanding on the previous Committee work (ISSC, 2018).
Moreover, when delivering the mandate of this work, the authors have acknowledged that potential overlaps may occur with regards to Committee III.1 Ultimate Strength, Committee III.2 Fatigue and Fracture, Committee IV.2 Design methods and Committee V.4 Offshore Renewable Energy. In this respect, all efforts have been made in order to minimize the overlap of work while if any of such similarities exist, this is done in the spirit of complementarity supporting the structural longevity of ship, offshore and any other marine structures as presented in this Committee’s mandate.
1.2 Report content
The present report consists of six chapters. Each chapter provides thorough critical examination of the available literature while useful conclusions and recommendations for future direction are provided at the end of the Committee report.
In this respect, following an introductory chapter that provides an overview on the Committee’s mandate and brief summary of the report content, Chapter 2 investigates the lifecycle assessment and management for structural longevity approaches and tools, considering the particular areas of lifecycle assessment and maintenance management. Data-driven maintenance and relevant approaches such as digital twin applications, iFEM, and reliability-based research efforts are covered as well.
In Chapter 3, the trends and developments in inspection and monitoring techniques to improve the structural longevity of ship and offshore structures are highlighted. These concepts are complemented by the examination of hull monitoring systems, remote and autonomous testing and sensors applications for structural monitoring; the employment of artificial intelligence (AI) applications and cloud-based data acquisition and management systems.
Chapter 4 specifically considers the models and applications developed in relation to offshore structures updating the work performed in the previous ISSC committee report. The review looks into the aspects of deterioration mechanisms (corrosion, crack growth, erosion and wear), mechanical limit states, implementation of methods and procedures for safe operation and aspects of risk-based integrity management of offshore structures.
Furthermore, Chapter 5 explores the available literature with regards to the ships and offshore structural longevity methods and examples. In particular covering the aspects of prediction of longevity, failure modes contributing to longevity assessment and also presenting a more detailed case of a polar supply and research vessel.
Finally, Chapter 6 summarises the concluding remarks of the structural longevity report and offers a number of recommendations and directions for future research and applications related to ship, offshore and other marine structures.