Uncertainty Quantification for Naval Ships and the Optimal Adaptation of Bridges to Climate Change

Repairing and adapting existing structures and infrastructure is essential for maintaining the functionality of a transportation network and the flow of people, goods, and ideas across a region. However, structures are vulnerable to extreme events, such as hurricanes and floods, and continuous deterioration, due to exposure to corrosive environments and cyclic loading. The occurrence of extreme events may be nonstationary over the service life of the structures, leading to uncertain future loading conditions on the structure. Continuous deterioration, due to corrosion or fatigue, changes the capacity of the structure to resist loads over time. Repair and adaptation measures may be applied to a structure in order to improve the capacity to resist loads. However, limited economic resources prohibit the immediate repair and adaptation of all structures, thus requiring a systematic methodology be established prioritizing actions. It is because of this need that the field of life-cycle management has emerged. The focus of the research in this dissertation is on enhancing this field and the ability of engineers to (1) quantify uncertainty in the life-cycle management problem, (2) assess the performance of structures and develop effective management strategies, and (3) integrate the uncertainties of climate changes and future loading conditions into the management of structures.Uncertainty quantification typically involves describing the variability in the loads acting on a structure, the capacity of the structure, and the deterioration over time of the structure. In the design phase, uncertainty quantification is based on observing loads in the area (traffic, wind, hydraulic loads, etc) and testing materials and connections to characterize their properties. In the operational phase, Structural Health Monitoring (SHM) data can be integrated into the uncertainty quantification process. This research specifically enhances the ability to integrate SHM data into the fatigue life prediction of ship structures and improve uncertainty quantification for naval ships.Life-cycle management integrates the quantifiable uncertainties into the performance assessment of a structure. For civil structures, hydraulic hazards like hurricanes, floods, and tsunamis may cause extensive damage; and failure may have major economic, societal, and environmental consequences. This research focuses on enhancing the performance assessment methodologies for evaluating the risk associated with the failure of riverine and coastal bridges once the uncertainties are known. The considerations for the multiple failure modes, as well as the multiple hazards, included in this research are shown to be essential when determining the risk level of bridges. Furthermore, this work includes proposed methodologies for determining optimal management strategies that are driven by both performance and cost in order to aid decision makers.The final thrust area of this research emanates from the uncertainties associated with anticipated climate changes. Natural and anthropogenic changes result in changes to sea level, the intensity of storms, and the intensity of precipitation which leave riverine and coastal bridges increasingly vulnerable. The uncertainties that govern the future variability in climate are currently reported as unquantifiable. This type of uncertainty is referred to as a deep uncertainty and stems from the multiple feasible projections for gas concentrations and the multiple available climate models with which to evaluate them. This research introduces a systematic decision support framework for determining adaptation strategies in the presence of both the deep uncertainties of climate change and the quantifiable uncertainties of structural performanc

Life-cycle maintenance, monitoring, and inspection optimization for ship structures under uncertainty

This paper presents a probabilistic optimization approach for scheduling inspections, monitoring, and maintenance actions along the life-cycle of ships under fatigue deterioration. The optimization approach yields the optimum interventions times and types that facilitate the minimization of expected life-cycle maintenance and inspection cost, maximization of expected service life, and minimization of expected failure cost. Uncertainties associated with the performance prediction, service life estimation with and without maintenance, and the relationship between the degree of damage and the probability of damage detection are considered in the proposed approach. Computing the life-cycle cost, failure cost, and service life is based on an event tree model which takes into consideration the different outcomes of inspection and monitoring actions. The proposed approach is applied to a ship structure under fatigue deterioration.Non UBCUnreviewedThis collection contains the proceedings of ICASP12, the 12th International Conference on Applications of Statistics and Probability in Civil Engineering held in Vancouver, Canada on July 12-15, 2015. Abstracts were peer-reviewed and authors of accepted abstracts were invited to submit full papers. Also full papers were peer reviewed. The editor for this collection is Professor Terje Haukaas, Department of Civil Engineering, UBC Vancouver.FacultyResearche