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During the past few decades, there have been many instances of significant damage to coastal infrastructure, especially bridges, due to ocean waves generated by hurricanes and tsunamis. Since ocean waves and currents co-exist and twist with each other in natural marine environments and their interaction may result in more severe damaging waves, taking both of them and their interaction into account is important in better understanding of damage processes of coastal bridges. This paper conducts a numerical investigation on hydrodynamic load on a bridge deck due to joint action of solitary waves and currents. Effects of prominent factors including current velocity, submersion depth, wave height, and water depth have been studied. Efficiency of air vents in reducing the hydrodynamic load has also been discussed. The numerical investigation indicates that, in a linearly pattern, a current in the wave direction leads to a higher maximum of the hydrodynamic force in the horizontal direction, and a current in the opposite direction results in a lower maximum. However, the behaviors of other characteristics of the force, including the maximum of its vertical component and the minimums of its horizontal and vertical components, become complicated and highly nonlinear because of water overtopping on the deck. In addition, a current can play a pronounced role, either positive or negative, in efficiency of air vents in reducing the hydrodynamic load. It is anticipated that the findings in this paper will enhance our understanding on mechanism of bridge damage by waves and may also be useful in design of future coastal bridges. [ABSTRACT FROM AUTHOR]

To protect the coastal communities and infrastructures from the devastating damages caused by the extreme ocean surface waves during the severe weather conditions, many coastal defense structures, such as seawall, have been widely constructed along the coastline. In fact, huge ocean surface waves and strong onshore winds coexist in the real harsh coastal environment. Hence, it is of significant necessity to accurately evaluate the overtopping characteristics of coastal defense structures under the combined impact of waves and onshore wind. In this paper, overtopping characteristics of the coastal seawalls under the combined impact of onshore wind and solitary wave are numerically studied. Influences of some main factors, such as onshore wind speed, water depth, wave height, beach slope, and seawall slope, are discussed in detail. The results show that the presence of onshore wind can greatly affect the runup and the amount of overtopping water of seawall under the action of solitary wave. It is hoped that the results of this paper will further deepen our understanding of the overtopping characteristics of seawalls during the severe weather conditions. • ▪Transformation and overtopping properties of solitary wave over the seawall under the influence of onshore wind are investigated by applying a two-phase numerical wind-wave tank. • ▪Effects of prominent factors, such as wind speed, wave height, water depth, beach slope, and side slope of the seawall are discussed in details. • ▪Results indicates that the existence of onshore wind can significantly enhance the impacting loads and increase the overtopping water of the seawall under solitary wave. [ABSTRACT FROM AUTHOR]

When hydrodynamic loads of the bridge deck exerted by extreme surges and waves exceed the restraining capacity of the superstructure and substructure, bridge deck will be pushed off from the substructure. However, before the final failure of coastal bridge deck, its dynamic behavior can be idealized as a mass-spring-damper system. In the harsh ocean environment, extreme surges and waves coexist. It is their joint impact that has finally caused the damages of the coastal bridges. In previous studies, only the damage effect of ocean surface waves on the movable bridge deck was considered, and the influence of background current was not considered. In this study, hydrodynamic characteristics of movable coastal bridge deck under joint impact of solitary wave and current have been well investigated. Effects of the wave height, water depth, submersion depth, background current speed, and lateral stiffness on the hydrodynamic characteristics of movable coastal bridge deck were systematically analyzed. The results indicate that the existence of background current can significantly influence the hydrodynamic characteristics and dynamic responses of movable bridge deck under the action of solitary wave. The effective wave celerity gradually increases with background current speed, which eventually enhances the horizontal load and lateral displacement of the movable bridge deck, and it finally increases the potential risk of bridge damage. • Hydrodynamic characteristics of movable bridge deck under the joint impact of solitary wave and current have been investigated considering the effects of wave height, water depth, submersion depth, background current speed, and lateral stiffness. • ▪Results indicate that the existence of background current can significantly influence the hydrodynamic characteristics of movable bridge deck under the impact of solitary wave, increasing the potential risk of bridge damage. • ▪Although the lateral stiffness of the bridge deck has significant impact on the lateral displacement, it has limited influences on the peak values of both horizontal and vertical loads of the movable bridge deck. [ABSTRACT FROM AUTHOR]

Extreme ocean surface waves generated during hurricanes or tsunamis can cause severe damage to coastal communities and infrastructures, especially coastal bridges. In this paper, installation of floating breakwater is proposed to protect coastal bridge decks against strong ocean surface waves. As an environmental-friendly wave-reduction device, floating breakwaters can be easily installed and removed before and after a storm, avoiding impacts on navigation and other coastal operations. To numerically investigate effects of a floating breakwater on the applied hydrodynamic load of a bridge deck under the impact of cnoidal waves, a high-resolution numerical wave tank (NWT) is established using the open-source flow solver REEF3D, which solves the governing equations of the incompressible two-phase flow on a staggered mesh and captures the interface between air and water using a high-resolution level-set method. Effects of prominent parameters, i.e. wave height, water depth, submersion depth, spacing distance and aspect ratio of breakwaters, on the performance of floating breakwater and reducing the hydrodynamic load on a coastal bridge deck are systematically analyzed. It is found that hydrodynamic loads of coastal bridge deck can be greatly reduced through the use of floating breakwaters. Results of this paper can further enhance our understanding on the damage mechanism of coastal bridges under extreme surge waves, and should be instructive for future bridge design. • A high-resolution numerical wave tank is established by using the open-source flow solver REEF3D, which numerically solves the governing equations of the incompressible two-phase flow on a staggered mesh arrangement. • Computational capability of our numerical wave tank is well calibrated by simulating cnoidal waves impacting bridge deck model and 3DOF motions of floating breakwater under regular waves. • Effects of floating breakwater on hydrodynamical load of low-lying bridge deck under impact of cnoidal wave have been systematically studied by considering several prominent factors. [ABSTRACT FROM AUTHOR]