Al-Wazeer, Adel Abdel-RahmanThe aging of bridges and traffic volume increase result in deterioration of bridge conditions and consequently increased risks to bridges and users. Highway agencies in the United States face challenges because of lack of sufficient resources to maintain bridges in good conditions. Current bridge management practices use cost as the main factor for determining maintenance strategies for bridges. Bridge management methods that identify bridges based on risk considerations and produce cost-effective maintenance strategies are needed to best utilize limited resources for reducing risks associated with bridge conditions. This dissertation proposes and demonstrates a methodology for defining bridge maintenance strategies based on risks associated with conditions of bridge elements and costs needed to improve these conditions. The methodology is a systematic approach for assessing risks to bridge elements based on their failure probabilities and consequences and managing associated risks using cost-effective maintenance strategies. The proposed methodology defines maintenance scenarios, optimal policies that minimize cost of maintenance and risks to elements, and optimal timing for implementing or deferring maintenance policies. The element-level maintenance policies in the proposed methodology are integrated with bridge-level priority ranking to define practical maintenance strategies for an inventory of bridges. The bridges are prioritized for maintenance according to their risk values and risk-reduction effectiveness of their maintenance policies based on benefit-cost analysis. The proposed methodology builds on existing bridge management methods, and allows for the use of risks associated with bridge conditions to assist in making risk-informed decisions for allocating limited resources for cost-effective maintenance strategies of bridges most in need. The study showed that risk is a viable tool for managing the maintenance of bridges in a cost-effective manner. The case study showed that the proposed methodology is feasible and can be implemented in currently used bridge management systems.en-USDissertationEngineering, Civil