Date

2016

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Civil Engineering

First Adviser

Frangopol, Dan M.

Other advisers/committee members

Yen, Ben T.; Bocchini, Paolo; Cheng, Liang

Abstract

During their service life, structural systems (e.g., civil and marine structures) may be subjected to aggressive deteriorations such as corrosion and fatigue and/or extreme events such as floods, collisions, earthquakes, and fires. These deteriorations may start from the day the structures enter in service and, if not effectively managed, can cause a significant reduction in structural functionality and safety. Maintaining performance and functionality of structural systems under these adverse effects is gaining increased attention. This highlights the necessity of effective assessment and management of civil and marine structures in a life-cycle context.The main objective of this study is to develop a risk, sustainability and resilience-informed approach for the life-cycle management of structural systems with emphasis on highway bridges, bridge networks, buildings, interdependent structural systems, and ship structures. Risk - based performance indicators combining the probability of structural failure with the consequences associated with a particular failure event are investigated in this study. Furthermore, a wide range of performance measures is covered under “sustainability” to reflect three aspects: economic, social, and environmental. Sustainability is described as “meeting the needs of present without altering the needs of future generations” (Adams 2006). Sustainability can serve as a useful tool in decision making and risk mitigation associated with civil and marine structures. In addition to risk and sustainability, resilience is another indicator that accounts for structural functionality and recovery patterns after extreme events. Presidential Policy Directive (PPD 2013) defines resilience as “a structure’s ability to prepare for and adapt to changing conditions while simultaneously being able to withstand and recover rapidly from functionality disruptions”. Overall, risk, sustainability, and resilience assessment considering aging and multi-hazard effects are of vital importance to ensure structural safety and functionality of structural systems during their service life.Risk is assessed for highway bridges under the effects of climate change and multiple hazards, including aging effects, flood-induced scour, and earthquake, whereas the adverse effects associated with aging and earthquake are investigated for bridge networks. The sustainability of highway bridges and bridge networks is assessed considering social, economic, and environmental metrics. The seismic resilience of highway bridges under mainshock (MS) only and mainshock-aftershock (MSAS) sequences is investigated to account for structural performance and recovery patterns under extreme events. Additionally, the seismic performance of buildings and interdependent healthcare - bridge network systems is investigated considering correlation effects and uncertainties. Furthermore, a probabilistic methodology to establish optimum pre-earthquake retrofit plans of bridge networks based on risk and sustainability is developed. For ship structures, a decision support system considering structural deteriorations (i.e., corrosion and fatigue) and extreme events (e.g., collision) is established. Specifically, the probabilistic ship collision risk and sustainability are investigated incorporating the attitude of a decision maker. A novel approach is developed to evaluate the time-variant risk of ship structures under corrosion and fatigue during the investigated time interval. Furthermore, a multi-objective optimization problem, which accounts for structural deteriorations and various uncertainties, is formulated to determine optimum inspection planning that reduces the extent of adverse consequence associated with ship failure while simultaneously minimizing the expected total maintenance cost. Additionally, a probabilistic approach for reliability and risk updating of both inspected and uninspected fatigue-sensitive details at both component and system levels is developed considering uncertainties and correlation effects. Overall, this study provides methodologies for the risk, sustainability, and resilience-informed assessment and management of structural systems under structural deteriorations and extreme events in a life-cycle context. Based on the inspection information, the reliability and risk could be updated for the near real-time decision making of deteriorating structures. The proposed probabilistic frameworks are illustrated on highway bridges, bridge networks, buildings, interdependent structural systems, and ship structures. The proposed methodology can be used to assist decision making regarding risk mitigation activities and, ultimately, improve the sustainability of structural systems in a life-cycle context.

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