MONITORING OF STRUCTURAL HEALTH AND DANGER STATE FOR SAFETY AND SUSTAINABILITY OF INFRASTRUCTURE SYSTEMS
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This dissertation is on monitoring of structural health and danger state for safety and sustainability of infrastructure systems. It consists of a synopsis, in addition to journal and conference papers and manuscripts. The general considerations for structural health monitoring (SHM) of infrastructure systems are introduced, as well as the monitoring of dangers relevant to structural safety. Danger state monitoring (DSM) is defined along with related terms. The integration of these two monitoring systems with consideration of multi-hazards is described and termed as structural health and safety monitoring (SHSM). Next, the perspective of dams and reservoirs is discussed, with an outline of geohazards and definition of a dam SHM. The case in Iceland of Hálslón Reservoir and its dams is introduced. This case discusses the aspects of concrete faced rockfill dams (CFRDs) in conjunction with the main dam. Finally, the synopsis is related to the main research, which encompasses two studies, referred to as Study A and Study B. Study A relates to elements of a dam SHM. The study focuses on the settlement behaviour of Hálslón Reservoir’s main dam, a CFRD, statistical analysis of settlement data, and development of a statistical prediction model considering visco-elasto-plastic constitutive material models and unloading/reloading behaviour. The study brings forth the importance of scrutinizing and processing raw readings and data from full-scale monitoring instrumentation. It further shows that statistical analysis provides a means to compare responses from many instruments at different locations. This comparison aids in defining trends in a data set, seasonal components, changes in behaviour and/or outliers. Additionally, the analysis produces details for a comprehensive understanding of dam settlement behaviour. Study B relates to elements of DSM as well as SHSM with regard to multi-hazards. The study focuses on geodangers that may threaten reservoirs and dams and the associated hazards (termed geohazards). The planning and organization of a danger-monitoring program is described and explained through the case of Hálslón Reservoir. Subsequently, geohazards and their monitoring are defined in the general context of reservoirs and dams. A new methodology is set out for enhancing safety by linking multi-source monitoring to multihazards threatening infrastructure systems. An application of the methodology is demonstrated with a conceptual model of two systems. One system includes the infrastructure, a reservoir and its dams, along with settings for geohazards. The other system contains the associated monitoring. Interrelations between and within the two systems are quantitatively explored by applying an existing method of systems theory, extended to include multiple systems. This is used to investigate hazard-triggering potential, interaction intensity and dominance. It is further used to explore the reaction of monitoring components to geohazard action as well as safety values of the monitoring system and its components. The interrelations established have general relevance to reservoirs and dams. A case study illustrates these points. Moreover, the interrelations can be used for defining hazard chains in multi-hazard assessment, planning of monitoring programs and detecting precursory pathways within a monitoring system. The methodology constitutes the basis for comprehensive safety and risk management, embracing multi-hazard assessment as well as structural health monitoring.