Coastal Bridge Deck Research Articles

Discussion of “Numerical Investigation of Connection Forces of a Coastal Bridge Deck Impacted by Solitary Waves” by Yalong Cai, A. Agrawal, Ke Qu, and H. S. Tang

Discussion of “Numerical Investigation of Connection Forces of a Coastal Bridge Deck Impacted by Solitary Waves” by Yalong Cai, A. Agrawal, Ke Qu, and H. S. Tang

Interaction mechanisms among waves, currents and a submerged plate

Wave-induced loads on a submerged plate, representative of submerged breakwater, coastal-bridge deck and a certain type of wave energy converter, in a uniform current are investigated in this study using fully nonlinear numerical wave tanks (NWTs) based on potential flow theory. The coupling effect of wave and current is explored, and the underlying interaction mechanisms of the hydrodynamic forces are described. The presence of a background current modifies the frequency dispersion. It produces changes of the water-surface elevation, and also has an effect on wave-induced loads. Depending on the nonlinearity, higher harmonic wave components are generated above the submerged plate. These contribute to the wave forces. It is found that the horizontal and the vertical force, hence the moment, are affected in the opposite way by the currents. The Doppler shifted effect dominates the vertical force and the moment on the plate. Whereas, the Doppler shifted effect and the generation of higher wave harmonics play opposite roles on the horizontal forces. The contribution of 2nd order harmonics is found to be up to 30% of the linear component. The current-induced drag force, represented by the advection term ρU∂φ/∂x in the pressure equation, is found to lead to a decrease in the moment for the most range of wavelengths considered, and an increase in the moment for a small range of longer waves.

Tsunami Forces on a Coastal Bridge Deck with a Box Girder

Tsunami Forces on a Coastal Bridge Deck with a Box Girder

Effect of Girder Spacing and Depth on the Solitary Wave Impact on Coastal Bridge Deck for Different Airgaps

Coastal bridge damage has become a severe issue of concern in the recent past with the destruction of a considerable number of bridges under the impact of waves during tsunami and storm surges. These events have become more frequent, with waves reaching the bridge deck and causing upliftment and destruction. Past studies have demonstrated the establishment of various theoretical equations which works well for the submerged deck and regular wave types but show much scatter and uncertainty in case of a deck that is above still water level (SWL). The present study aims to generate a solitary wave to represent an extreme wave condition like a tsunami in the numerical wave tank modeled using the open source computational fluid dynamics (CFD) model REEF3D and to study the vertical impact force on the coastal bridge deck. A parametric study is carried out for increasing wave heights, girders spacing and depth for varying airgaps to analyze the effect of these parameters on the peak vertical impact force. It is observed that increasing the girder spacing and girder depth is effective in reducing the peak vertical impact force for the cases considered.

Experimental Investigation of Wave Forces on Coastal Bridge Decks Subjected to Oblique Wave Attack

AbstractLarge wave forces induced by the combination of storm surge and hurricane waves have caused significant damage and failure of various coastal bridges in the Gulf of Mexico. Existing researc...

NUMERICAL MODELLING OF SOLITARY AND FOCUSED WAVE FORCES ON COASTAL-BRIDGE DECK

In the recent past, coastal bridges have been subjected to critical damage due to extreme wave attacks during natural calamities like storm surge and tsunami. Various numerical and experimental studies have suggested different empirical equations for wave impact on deck. However, they do not account the velocities of the wave type properly, which requires a detailed investigation to study the impact of extreme waves on decks. Solitary wave assumption is more suitable for shallow water waves, while the focused wave has been used widely to represent extreme waves. The present study aims to investigate the focused wave impact on coastal bridge deck using REEF3D (Bihs et al., 2016).

Influence of Current Velocity on Wave-Current Forces on Coastal Bridge Decks with Box Girders

Influence of Current Velocity on Wave-Current Forces on Coastal Bridge Decks with Box Girders

Semi-implicit non-hydrostatic model for 2D nonlinear wave interaction with a floating/suspended structure

A non-hydrostatic model is developed to simulate two-dimensional (2D) nonlinear wave interaction with a fixed floating/suspended structure. The immersed boundary method is incorporated in the model to address arbitrary body surfaces. The model employs a semi-implicit, fractional step algorithm to solve the Reynolds-averaged Navier–Stokes (RANS) equations based on a grid system, which is built from a horizontal rectangular grid by adding dozens of horizontal layers. The horizontal layers are distributed following a general boundary-fitted vertical coordinate system. This grid system may overcome the lack of flexibility of other boundary-fitted coordinate systems (e.g., the σ-coordinate system). The model is validated by using three test cases, namely, a solitary wave interacting with a floating rectangular obstacle, a solitary wave incident on a suspended horizontal plate and a solitary wave incident on a coastal-bridge deck with girders. Numerical results of the free surface elevation and wave force exerted on each structure are compared with the results of other models or experimental data. Generally, good agreements are obtained, demonstrating the proposed model’s capability to resolve nonlinear wave interactions with floating/suspended structures. The velocity fields around the structures are also presented and discussed.

Prediction of Solitary Wave Forces on Coastal Bridge Decks Using Artificial Neural Networks

Prediction of Solitary Wave Forces on Coastal Bridge Decks Using Artificial Neural Networks

Numerical Investigation of Connection Forces of a Coastal Bridge Deck Impacted by Solitary Waves

Numerical Investigation of Connection Forces of a Coastal Bridge Deck Impacted by Solitary Waves

Review of Wave Loads on Coastal Bridge Decks

Recent natural extreme events, such as Hurricane Ike in the U.S. (2008), Tohoku tsunami in Japan (2011), and Typhoon Haiyan in Southeast Asia (2013), have caused significant damage to the decks of coastal bridges. The failure of the structure occurs when wave-induced loads on the decks of coastal bridges exceed the bridge capacity, resulting in partial removal or a complete collapse of bridge decks. Tsunami, storm waves, and storm surge are known to be the ultimate agents of such failures. An understanding of the failure mechanism and possible solutions require a better knowledge of the destructive loads on the structure. Interaction of surface waves with the bridge deck is a complex problem, involving fluid–structure interaction, wave breaking, and overtopping. Possible submergence of the deck and entrapment of air pockets between girders can increase destructive forces and add to the complexities of the problem. In recent years, remarkable progress has been made on this topic, resulting in some new findings about the failure mechanism and the destructive wave loads. A review of the key studies on wave loads on the coastal bridge decks, including those in the past and very recently, is presented here. Emphasis is given to the pioneering works that have significantly improved our understanding of the problem. Challenges associated with the existing solutions are highlighted, and suggestions for future studies are provided.

Numerical prediction of solitary wave forces on a typical coastal bridge deck with girders

In this study, a numerical method for predicting solitary wave forces on a typical coastal bridge deck with girders is utilised in order to obtain an alternative way to assess solitary wave forces on coastal bridge decks with sufficient accuracy. Firstly, a wave model based on the solitary wave theory representing the incident wave of tsunamis is applied through a computational fluid dynamics computer program, where the shear stress transport k-ω model is adopted as the turbulent closure for the Reynolds Averaged Navier–Stokes model equations. Then, the numerical wave profiles and the predicted wave forces are compared with the analytical solutions and the reported laboratory measurements, respectively. These verifications assure the results in the following parametric study reliable. Finally, comparisons between the numerical results and those acquired through the empirical methods are conducted in order to examine the appropriateness of these empirical procedures regarding this specific case. Furthermore, an expanded formula is proposed with the definitions of the key parameters being discussed thereafter. This method can be expanded to cases where different deck cross sections rather than the typical one used in the present study are considered and to scenarios where different wave parameters are involved. It is hoped that the expanded formula could provide straightforward but advisable results for practicing engineers.

Component Level–Based Assessment of the Solitary Wave Forces on a Typical Coastal Bridge Deck and the Countermeasure of Air Venting Holes

AbstractIn this paper, the solitary wave forces on a typical coastal bridge deck are evaluated numerically based on a component level assessment, and the countermeasure of the air venting holes is investigated. At first, a wave model based on the second-order solitary wave theory is presented to represent the incident waves in tsunami events. The shear stress transport (SST) k-ω model is used as the turbulence closure for the Reynolds-averaged Navier-Stokes (RANS) equations. Then, the characteristics of the wave forces (the horizontal force, the vertical force, and the moment) considering three different still-water levels (SWLs) and four wave heights for each SWL are investigated, and the effects of the SWLs and wave heights are demonstrated. In addition, a component level–based assessment of the wave loadings, especially the overturning moment, varying along the wave propagation is conducted to enhance the understanding of the force distribution on the bridge deck. Finally, the countermeasure of the air...

Wave loads on a coastal bridge deck and the role of entrapped air

Wave loading on a coastal bridge deck due to nonlinear waves during a storm, where air may be fully or partially trapped between the girders, is studied through an extensive set of laboratory experiments. Wave cases tested cover a range of shallow-water to intermediate-water depth waves. A range of model elevations is tested to include conditions where the bridge may be partially inundated, to where the model is fully elevated above the still-water level (SWL). The model is constructed to include different percentages of air-relief openings, to capture a range of cases where no air can escape between the girders, to where all the air can escape and the wave can freely interact with the bottom of the bridge deck. Effects of the compressibility of entrapped air as well as the effects of the model scale are investigated through numerical calculations solving the compressible and incompressible Euler's equations, at both the model and prototype scales, by use of the open source CFD software, OpenFOAM. Along with coastal bridges, this research is applicable to other coastal and offshore structures, such as piers, submerged breakwaters and offshore platforms, in which wave loading or entrapped air is of concern.

Effect of Entrapped Air on Solitary Wave Forces on a Coastal Bridge Deck with Girders

AbstractRecent tsunami and hurricane-caused destruction, and the possibility of both tsunami inundation and storms of even greater magnitude and frequency making landfall in the future, has focused attention on the vulnerability of coastal structures, and bridges in particular. Findings from a series of experiments measuring forces on a 1:35 scale bridge model impacted by a solitary wave with varying percentages of air relief openings (AROs) between girders are presented here. A range of water depths, wave amplitudes, and elevations of the model above the still-water level (SWL) are considered. Results show significant reduction of vertical uplift forces when AROs are added to the bridge model, particularly when the girders are fully elevated above the SWL or only slightly submerged, but relatively little effect on horizontal forces in the direction of wave propagation is observed. Buoyancy calculations show added hydrostatic force does not alone contribute to uplift forces, but rather a combination of hy...

Experiments and calculations of cnoidal wave loads on a coastal-bridge deck with girders

Horizontal and vertical forces on a 1:35 scale model of a typical two-lane coastal bridge due to cnoidal wave loads are investigated by conducting an extensive set of laboratory experiments and comparing the resulting data with CFD calculations and existing simplified, design-type equations. The experimental parameters tested cover a wide range of wave and inundation conditions that may occur during a major storm or hurricane. This includes a wave matrix of 40 waves and bridge model elevations covering a range where the top of the bridge is fully submerged below the still-water level (SWL) to where the bottom of the girders are elevated above the SWL. Measurements for surface elevation, vertical and horizontal forces are compared with calculations made by solving Euler’s equations using the CFD software OpenFOAM with good agreement. Vertical uplift and horizontal positive forces (forces measured in the direction of wave propagation) are compared with the simplified equations using the relations given in Douglass et al. (2006). This set of data provides a valuable benchmark for understanding wave loads on coastal bridges during a storm or hurricane.

Experiments and calculations of cnoidal wave loads on a flat plate in shallow-water

Horizontal and vertical wave forces due to the interaction of cnoidal waves with a two-dimensional, horizontal flat plate located in shallow-water are studied through laboratory experiments and calculations. The experiments are conducted for a combination of two water depths, five wavelengths and four wave heights, corresponding to the propagation of nonlinear waves in shallow-water depth. The model is located at six different elevations and submergence depths such that all possible cases of a coastal bridge deck fully above the still-water level, a deck on the surface and a fully submerged deck are considered in the study. Calculations are performed for the same cases as in the laboratory experiments and include the results of a nonlinear shallow-water wave model based on the Level I Green–Naghdi equations for the fully submerged cases, and Euler’s equations coupled with the Volume of Fluid interface tracking method for one submerged case, one elevated case, and one case at the water surface. Comparison of existing theoretical solutions are also provided, including the Long-Wave Approximation based on linear potential theory for the submerged cases, and empirical relations for the elevated cases. The set of data presented here provides an insight into storm wave loads on the decks of coastal bridges, jetties and piers located in shallow-water areas.

Experiments and computations of solitary-wave forces on a coastal-bridge deck. Part II: Deck with girders

Solitary wave-induced forces on a two-dimensional model of a coastal bridge are investigated by conducting laboratory experiments and performing CFD computations. Experimental parameters included four water depths, five wave amplitudes, four submergence depths and three elevations above the still-water level (SWL), for a total of 118 cases. Submergence depths and elevations are chosen such that the bridge model may be fully submerged, partially inundated or fully elevated above the SWL. Euler's equations are solved by use of the CFD program OpenFOAM to compute the wave forces. It is found that the forces calculated by OpenFOAM are in close agreement with the laboratory measurements in most cases. The effect of formation of entrapped air pockets on the wave forces is studied by including air pressure relief openings on the deck of the model. This paper is a companion to Part I under the same title. The forces on the deck with girders are compared with those on the flat plate (given in Part I) to examine the role of girders on the forces. The solitary wave forces are further studied computationally by changing the number of girders in different submergence depths.

Experiments and computations of solitary-wave forces on a coastal-bridge deck. Part I: Flat Plate

Horizontal and vertical forces acting on a two-dimensional horizontal plate due to solitary waves are investigated by conducting a series of laboratory experiments as well as CFD calculations. A total of 133 cases were tested, including four water depths, four submergence depths and three elevations above the SWL, and five wave amplitudes. Following the experiments, computational results obtained by the CFD package OpenFOAM are presented for both vertical and horizontal forces. The comparisons made with the calculations show that OpenFOAM's InterFoam solver, that we specialized to Euler's equations here, can successfully simulate the data in many cases. With the wave force data presented here, it will now be possible to compare numerical predictions of various shallow-water wave equations with the experiments. The data will also be useful to estimate the tsunami loads on submerged structures, such as breakwaters, and elevated structures, such as coastal-bridge decks. The case of the flat plate, either submerged or elevated, is considered in this paper (Part I), while the case of a plate with girders will be discussed in a companion paper under the same title (Part II).

An investigation of plane water-lines for ships

Wave loading on a coastal bridge deck due to nonlinear waves during a storm, where air may be fully or partially trapped between the girders, is studied through an extensive set of laboratory experiments. Wave cases tested cover a range of shallow-water to intermediate-water depth waves. A range of model elevations is tested to include conditions where the bridge may be partially inundated, to where the model is fully elevated above the still-water level (SWL). The model is constructed to include different percentages of air-relief openings, to capture a range of cases where no air can escape between the girders, to where all the air can escape and the wave can freely interact with the bottom of the bridge deck. Effects of the compressibility of entrapped air as well as the effects of the model scale are investigated through numerical calculations solving the compressible and incompressible Euler's equations, at both the model and prototype scales, by use of the open source CFD software, OpenFOAM. Along with coastal bridges, this research is applicable to other coastal and offshore structures, such as piers, submerged breakwaters and offshore platforms, in which wave loading or entrapped air is of concern.