Portland State University. Department of Civil & Environmental Engineering
Term of Graduation
Date of Publication
Doctor of Philosophy (Ph.D.) in Civil & Environmental Engineering
Civil and Environmental Engineering
Fluid-structure interaction, Bridges -- Vibration, Ocean waves, Storm surges, Structural engineering
1 online resource (ix, 124 pages)
Bridges are critical lifeline components of the infrastructure network, enabling economies to function under normal conditions and disaster response and recovery missions to take place after extreme events. Therefore, ensuring satisfactory performance increases community resilience and minimizes both human and economic losses. Coastal bridges, which are the focus of this PhD dissertation, are vulnerable to coastal storms. High failure rates of these bridges during two major hurricane events in the mid-2000s have spurred research activities to better understand the wave-induced forces of coastal bridges.
This PhD research represents a continuation effort to build, implement, and introduce new fundamental concepts and methods that are important to the bridge engineering community. The data set analyzed was part of an experimental study conducted at the O. H. Hinsdale Wave Research Laboratory at Oregon State University in 2007. A unique aspect of the setup was that the substructure flexibility of the 1:5-scale bridge specimen could be adjusted by inserting springs with different stiffnesses. The realistic specimen was subjected to a range of wave conditions, water levels, and substructure fixity conditions.
First, a suitable equation of motion was developed as it represents an essential building block for any planned simulation effort. This equation was derived based on the examination of the damping behavior of the system. This effort lead to a better understanding of how the dynamic properties of the bridge superstructure specimen are affected by different levels of submersion, and what their numerical values are.
Second, the available data set was analyzed in depth with the objective to determine the effect of substructure flexibility on the observed wave-induced forces on the bridge superstructure specimen. Reinforced by the test of restriction, it was found that the measured forces experienced by the superstructure specimen with a flexible substructure were notably larger compared to the rigid case. These findings highlight the need to account for substructure flexibility when estimating wave forces. The proposed force magnification factors can be used in conjunction with code equations that are based on rigid support conditions.
Finally, in order to expand the understanding of substructure flexibility and exploring test conditions that are not part of the original experimental dataset, having a numerical model is a promising solution. The particle finite element method (PFEM) was selected as the tool for this purpose and is introduced and evaluated against sample responses from the experiment.
In conclusion, support conditions affect the dynamic response of bridges subjected to wave action and thus need to be considered. This PhD dissertation created a better fundamental understanding of how bridges respond dynamically to wave action considering varying levels of submersion as well as substructure flexibility. The findings allow bridge engineers to build more accurate numerical models for fluid-structure interaction problems and provide practical guidance with respect to the magnification of wave-induced forces for design and evaluation applications.
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Hameed, Alaa Waleed, "Dynamic Response of Highway Bridge Superstructures Subjected to Wave Action: Experimental Analysis and Numerical Modeling" (2020). Dissertations and Theses. Paper 5489.
Available for download on Tuesday, June 22, 2021