Structural Integrity Management Of Offshore Engineering Based On The Value Of Health Monitoring Information

Structural integrity management is a dynamic decision-making process to ensure that engineering structures continue to meet their functional requirements throughout their life cycle.For offshore structures,safe,economical and stable operation throughout service life is the fundamental functional requirement.However,due to the uncertainty of construction materials and service environment,as well as the complex loading effects during the service life,the service life risks of offshore structures are huge.Therefore,it is important to develop a reasonable operation and maintenance strategy to reduce the risk according to its own characteristics.The observations related to the performance of offshore structures are beneficial to reduce the uncertainty existing in the operation process,and therefore structural health monitoring(SHM)systems have been widely used in offshore structures to provide significant decision support to operation and maintenance strategy.However,in order to efficiently use this information to truly improve decision making,it is crucial to quantify the economic benefits from a utility theory perspective for the integrity management of offshore structures.A quantitative analysis of the economic value of SHM systems can help decision makers to use SHM information more rationally to the management of offshore structures.Therefore,an application and research framework for analyzing the value of different types of SHM information can be used to optimize not only the arrangement of the SHM system itself,but also the structural integrity management of marine engineering in combination with SHM information.This thesis takes structural integrity management based on the value of SHM information as the main research object,and establishes the Vo I analysis of different SHM information and its application to structural integrity management based on structural reliability analysis and Bayesian preposterior decision analysis,the main contents are listed as follows:(1)The classification principles of SHM information are defined accounting for the application scenarios and roles of different kinds of SHM in the structural integrity management of offshore structures;the probabilistic modeling methods of different kinds of SHM information in the structural integrity management are presented considering the correlation of different SHM information in the spatio-temporal dimension and the uncertainty;meanwhile,the application scenario modeling methods of SHM information in the structural integrity management of offshore structures are studied considering the availability of SHM information.(2)A detailed Vo I analysis of load monitoring information for the structural integrity management of offshore structure is presented.Based on the Vo I analysis,a analytical framework for load monitoring system implementation is proposed;accounting for the availability of load monitoring information in the operation process,two utilization strategies for applying load monitoring information are proposed,and the two strategies are compared and selected based on the Vo I analysis;furthermore,considering the contribution of inspection information in the operation process,an adaptive inspection and maintenance planning accounting for the inspection results is proposed,and the Vo I of the load monitoring system is analyzed in this framework.(3)The value of direct performance monitoring information in the structural integrity management is analyzed in detail.Considering the contribution of the direct performance monitoring information to the extension of the decision space,a decision scenario accounting for the direct performance monitoring information is proposed.Considering the time-varying monitoring performance of the SHM system,this thesis quantifies the impact of time-varying monitoring performance on the Vo I of the SHM system and the structural integrity management of offshore structure.(4)On the basis of the structural integrity management framework proposed in this thesis,the operation & management strategy of offshore wind turbine support structure is studied.By utilizing structural finite element analysis software and combining the statistical wind and wave data in the European North Sea region,the operation & management decision framework of offshore wind turbine is proposed.Further,the economic benefits brought by the fatigue stress monitoring system are quantified based on the Vo I analysis.