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Access Type
WSU Access
Date of Award
January 2024
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Civil and Environmental Engineering
First Advisor
Christopher Eamon
Abstract
This research focuses on developing and implementing a reliability-based design optimization (RBDO) approach for a steel girder bridge to minimize construction cost while allowing the structure to meet a specified reliability level under blast load. The blast resistance of a typical two-lane steel girder highway bridge structural system was modeled using a nonlinear finite element approach that considers material damage, fracture, and separation. Critical blast scenarios, based on field observations of terrorist attacks on bridges in Iraq, were assessed to define system failure in terms of practical emergency serviceability criteria. The study varied various design parameters, such as the number of girders, deck concrete strength, reinforcement ratio, slab thickness, girder and reinforcement yield strength, girder sectional dimensions, and pier column width, to evaluate blast resistance. The RBDO process adjusted design variables including the number of girders, yield stress, flange width, flange thickness, web thickness, web depth, and deck thickness to maintain a specific reliability index for blast resistance.A reliability model was developed for the probabilistic assessment of the bridge. A response surface was developed to model critical girder end displacement for use in the limit state function. Sensitivity analysis indicated that the system's blast capacity and reliability were primarily influenced by the number of girders and girder yield strength, with additional significant parameters including deck compressive strength, deck thickness, web stiffener width, and girder depth. Secondary parameters were deck reinforcement ratio and girder flange and web thickness, while deck reinforcement yield stress was found to be insignificant. The results show that the RBDO balances structural integrity and cost by adjusting bridge geometric and material strength design parameters, reliability index, and steel/concrete cost ratio. Effective increases in steel girder bridge blast reliability can be achieved by using smaller girder spacing, higher yield strength girders with lower depth, and a deck with lower compressive strength but greater thickness. This study provides recommendations for improving blast resistance and cost-effectiveness in steel girder bridge design.
Recommended Citation
Alsendi, Ahmad, "Development Of A Reliability Based Design Optimization Framework For Typical Steel Bridge Structures Subjected To Blast Loads" (2024). Wayne State University Dissertations. 4089.
https://digitalcommons.wayne.edu/oa_dissertations/4089
