Wave and Debris Loading in Developed Coastal Regions

Tsunami and storm-driven flows in developed coastal regions are estimated in engineering standards using the bare earth assumption, in which the fluid-structure interaction is not explicitly taken into consideration. The presence of structures in developed coastal regions has a significant effect on the water flow, affecting wave hydrodynamics, wave loading, and debris impacts on buildings. However, methods and general guidelines to assess the effect of building arrays in these flow conditions have not been fully developed. The objective of this dissertation is to understand the effect of a building array on (1) tsunami wave run-up loading and (2) flood debris impact loading on developed coasts. Data from both laboratory experiments and Computational Fluid Dynamics (CFD) simulations were obtained. Results from both the laboratory and the numerical tests show that tsunami wave run-up loading is reduced as more sheltering is given by the building array. Three different tsunami Load Reduction Factors (LRF) were defined, which show that most of the tsunami load reduction takes place in the first four rows. The effect of the building array on maximum inundation levels, maximum velocities, and maximum momentum flux is also analyzed. A brief analysis and discussion about the effect of the cross-shore distance between rows, the width of the structures in the frontmost row, and the offset between rows is also presented. This dissertation also investigates the probabilities of impact and magnitude of debris collisions within a building array. These probabilities were assessed using laboratory measurements of structural loading response, flow hydrodynamics, and video recordings of flow and debris transport and impact. A methodology based on a single degree of freedom structural system was implemented to estimate the applied debris impulse from collisions and to investigate the dynamical impact of waterborne debris on structures. Results show that both the debris collision probability and the collision impulse magnitude are significantly reduced as the number of sheltering rows increases. Using empirical exceedance probabilities of the applied debris impulse, a framework was developed to estimate the maximum structural loading response within a building array, along with a comparison to data and existing standards. The effect of the impact duration on the relation between the applied debris impulse and the maximum structural response is also discussed.