Date of Award
Anil K. Agrawal
Foundation reuse, Risk analysis, Highway bridge, Substructure, decision-making, Environmental impact assessment
According to the 2019 National Bridge Inventory data from Federal Highway Administration, the average age of highway bridges in the U.S.A. is 45 years, with almost 43% of existing highway bridges being older than 50 years, and eight percent of all U.S. national highway bridges being in poor condition. Foundation and substructure of existing highway bridges (over land and water) may have significant functional values even after being under service for decades. Reusing an existing bridge foundation during the reconstruction of a bridge (e.g., major rehabilitation, retrofitting, replacement of superstructure and substructure, and addition/removal of a span) has the potential for significant savings on total cost and construction time. However, because of uncertainties in the evaluation of integrity, durability, and load-carrying capacity of an existing foundation, an inevitable level of risk is inherently associated with their reuse. This risk may weigh on potential benefits of reuse of a bridge foundation during the decision making. Therefore, developing a comprehensive framework and procedure for studying the feasibility of foundation reuse is an important step in the foundation reuse decision process. In particular, bridge owners need to have an estimation of various risks associated with available options during a reconstruction project (i.e., fully reuse, partial reuse, and no- reuse).
In this dissertation, a decision-making framework is developed to evaluate the feasibility of reusing an existing foundation and substructure of highway bridges. This framework incorporates three factors including safety, cost, and environmental impacts of reusing an existing foundation and compares the available alternatives to find the most feasible alternative. Four general options in bridge reconstruction projects are defined. The time-dependent probability of failure, time-dependent consequences of failure, and subsequently time-dependent safety risk associated with available options are estimated using a comprehensive reliability-based approach. In the next step, bridge life-cycle costs of each of the options are estimated using deterministic and probabilistic approaches. Later, the environmental impacts of each option are estimated using Life-cycle Environmental Impact Assessment (LCIEA). The combination of results of risk analysis, bridge life-cycle costs analysis, and environmental impacts assessment of all options are used to compare the reuse attractiveness of four options. The comparison is conducted by implementing a pairwise comparison technique to incorporate three criteria of safety, life-cycle costs, and environmental impacts of each option. The final decision on the reuse of an existing bridge foundation is made using the Analytical Hierarchy Process (AHP). Finally, Oxford Valley Road Bridge over US-1 in Bucks County, PA is used as a case study to demonstrate application of the proposed framework.
Hoomaan, Ehssan, "Decision-Making in Reuse of Highway Bridge Foundations" (2020). CUNY Academic Works.