Effect on Risk Based Inspection of spatio-temporal dependence of ROC curves: Study of the corrosion of steel harbour structures
Owners of civil infrastructures base their maintenance decisions schemes mainly both on structural integrity assessment and consequence analysis. Some inputs come from information collected by non-destructive or destructive tools. Uncertainties and noise of measurements can lead to bad decisions but are rarely integrated into the process of decision. Nowadays, Risk Based Inspection (RBI) provides the basic concepts for optimizing the maintenance plans of existing structures while insuring a good safety and availability conditions during service life of structures. In this paper, concepts are applied on a steel sheet pile seawall submitted to uniform corrosion where spatio-temporal dependence of performance of ROC (Receiver Operating Characteristic) curves is studied. Résumé Les gestionnaires d’infrastructures de génie civil basent leurs schémas décisionnels de maintenance essentiellement à partir de l’évaluation de l’intégrité structurale des ouvrages et de l’analyse des conséquences en cas de défaillance. Certaines données d’entrée proviennent de contrôles destructifs ou non destructifs. Les incertitudes et le bruit sur les mesures peuvent conduire à de mauvaises décisions mais sont rarement pris en compte dans les processus de décision. Actuellement, les méthodes RBI (Risk Based Inspection) donnent les fondamentaux pour aboutir à des plans de maintenance optimisés tout en garantissant la sécurité et la disponibilité des ouvrages en service. Dans cet article, ces concepts sont appliqués à un quai constitué par un rideau de palplanches soumis à la corrosion uniforme et la dépendance spatio-temporelle de la performance des courbes ROC (Caractéristique Opérationnelle du Récepteur) est étudiée.
Applications of Statistics and Probability in Civil Engineering
Applications of Statistics and Probability in Civil Engineering contains the proceedings of the 11th International Conference on Applications of Statistics and Probability in Civil Engineering (ICASP11, Zürich, Switzerland, 1-4 August 2011). The book focuses not only on the more traditional technical issues, but also emphasizes the societal context of the decision making problems including the interaction between stakeholders. This holistic perspective supports the enhanced and sustainable allocation of limited resources for the improvement of safety, environment and economy. The book is of interest to researchers and scientists working in the field of risk and reliability in engineering; to professionals and engineers, including insurance and consulting companies working with natural hazards, design, operation and maintenance of civil engineering and industrial facilities; and to decision makers and professionals in the public sector, including nongovernmental organisations responsible for risk management in the public domain, e.g. building authorities, the health and safety executives, the United Nations and the World Economic Forum.
Fatigue crack growth in stiffened steel tubular joints in seawater environment
Welded steel tubular structures commonly used for offshore platforms are susceptible to fatigue failure due to stress concentration at welded joints and environmental loading which is cyclic in nature. Offshore structures contain flaws ranging from microscopic material defects to macroscopic geometric imperfections, due to fabrication and construction process. Such flaws can develop into cracks due to influence of cyclic wave loading in an aggressive marine environment. Due to this and many other causes, maintaining structural integrity of these structures has been a major concern for the oil industry. Hence a model for crack initiation life and crack growth life estimation has been developed by conducting constant amplitude corrosion fatigue tests on internally ring-stiffened steel tubular T and Y joints under freely corroding conditions. Biologically inert synthetic seawater was used as the corrosive environment. Tests in seawater were carried out with a loading frequency of 0.2 Hz. The studies were made with respect to tropical environment similar to Indian offshore. The corrosion fatigue crack growth data obtained during the tests and the Fracture Mechanics (FM) model developed are discussed in this paper.