This paper presents the results of a comprehensive experimental program focused on the impact of extreme hydrodynamic forces on structural models generated by a turbulent hydraulic bore. The parameters investigated include: (1) bore depth-time history; (2) initial flume-bed conditions (dry bed versus wet); and (3) damping effect of mitigation walls on the hydrodynamic forces. At impact, the maximum inundation (bore) depths varied between 250 mm and 450 mm and the bore front velocity ranged from 2.6 m/s to 5.0 m/s. High-speed video recordings of the bore-structural model interaction were captured simultaneously with the base shear force-, pressure-, base overturning moment-, and top lateral displacement-time histories experienced by the structural models. Three force components were identified in the bore-induced force-time histories: impulsive, run-up (transient hydrodynamic force), and quasi-steady hydrodynamic. The impulsive or run-up force was the maximum force component experienced by the structural models under initial dry-bed flume conditions; while for the initial wet-bed flume condition, the run-up force component was the maximum force. The effect of 100 mm and 150 mm low-height mitigation walls inclined at angles of 45° or 90°, which were installed at distances of 305 mm or 915 mm upstream from the structural model, was also investigated. The angle of inclination of the mitigation walls, its location relative to the structural model, and its cross-sectional shape all influence the base shear force- and base overturning moment-time histories. The base shear forces in the direction of the flow measured during experimental testing were greater than those estimated using the Federal Emergency Management Agency (FEMA) document P646, while the Structural Design Method of Buildings for Tsunami Resistance (SMBTR) overestimated the base shear forces.

Tsunamis, landslide-generated waves, and dam failures are rare, but highly destructive phenomena, associated with extreme loading on infrastructure. Recent events showed that specific measures must be taken to guarantee safety of both people and the built environment. This experimental study investigates the forces and moments exerted on free-standing buildings that are induced by both surges and bores. The hydrodynamic impact was characterized by high splash, subsequently followed by a quasi-steady flow around the structure. For dry bed surges, the time history of the horizontal force was proportional to the momentum flux per unit width. For wet bed bores, an attenuation of the peak force due to the presence of an aerated front was observed and the introduction of a reduction coefficient was necessary to achieve a realistic force estimation. Additional force analysis in terms of peak time, wave height at maximum force and impulse also pointed out some key differences between forces exerted by dry bed surges and wet bed bores. The occurrence of the maximum tilting moment on the building coincided with the maximum horizontal force and an evaluation of the cantilever arm was possible. These findings provide engineers with practical information for the design of safer coastal structures.

Tsunamis, impulse waves, and dam failures are disasters that challenge humanity, often leading to massive casualties and extreme economic losses. The highly unsteady flow conditions generated by such events are often in the form of turbulent bores. The purpose of this study was to investigate and validate a new generation system for bores propagating over dry and wet bed conditions. There are multiple techniques to generate such waves experimentally, and the study focused on the generation of tsunami-like inundation conditions through the vertical release of a water volume. A detailed methodology to characterize the generated waves hydraulically, in terms of their wave heights and flow velocities, is presented, and good agreement with the classical dam-break case for both dry bed surges and wet bed bores was demonstrated. Because of the importance of estimating the impact forces induced by such waves, particular attention was given to the wavefront celerity and the velocity profiles measured behind the wavefront; these were found in agreement with Prandtl’s power law for open channel flows, and in-depth measurements allowed for the definition of an expression to estimate flow deceleration behind the wavefront. Along with considerations of the Froude number and momentum, this paper provides relevant information to assist engineers in designing safer infrastructures in areas prone to such extreme loading.

Recent natural disasters, such as the 2004 Indian Ocean and 2011 Tohoku Tsunami, exhibited the importance of tsunami resistant infrastructure in high-risk coastal areas. The failure of critical infrastructure in tsunami-stricken communities has led to a recent emphasis on extreme loading conditions associated with tsunami events. One of the critical loads identified by previous research was debris loads. Debris is defined as solid objects entrained within the inundating flows and can range from construction materials to shipping vessels. The emphasis of tsunami loading has led to recent progression in the understanding of debris loads and effects, particularly in evaluating the impact of a single debris piece on a structure. The following paper reviews state-of-the-art research in tsunami-driven debris motion and loads and identifies future directions of research into debris loads and effects to aid in the design of tsunami-resistant infrastructure.

This study presents the results of an experimental research program dealing with spatial debris motion on a horizontal apron depicting a typical harbor wharf. Accordingly, scaled-down 6.1-m (20-ft) shipping containers were equipped with a novel yet nonintrusive real-time tracking system and motion sensors. The instrumentation allowed for the spatiotemporal tracking of debris specimens moving across the apron while entrained by an incoming tsunami-like broken bore. The system proved its capabilities and accuracy; this was particularly challenging since this was the first time the system was used in water. The experiments involved using various numbers of shipping containers that were either arranged in one layer or stacked in two layers. In addition, the effect of different numbers of container rows was also investigated to study the influence of the overall container count and placement with respect to their longitudinal displacement and dispersion (spreading) across the apron. Linear relationshi...