Masoud Hayatdavoodi

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.

Vulnerability assessment of coastal bridges on Oahu impacted by storm surge and waves

Vulnerability assessment of four selected prototype coastal bridges on the island of Oahu, Hawaii, to the combination of storm surge and waves is presented. The maximum storm surge condition is estimated by considering an extensive series of simulated hurricanes making landfall on the island of Oahu, where the bridges are located. For the given extreme environmental conditions, wave loads on the deck of the selected bridges are calculated by use of several theoretical and computational approaches, including Euler’s equations (OpenFOAM), the Green–Naghdi nonlinear equations, linear long-wave approximation and existing simplified, design-type force equations. Multiple scenarios of the relative location of the bridge deck and the still-water level are studied to determine the maximum possible wave loads on the bridge decks. Vulnerability of the coastal bridges to storm wave loads is determined by comparing the capacity of the bridge to the wave-induced loads on the structure.

A Comparative Study of Nonlinear Shallow-Water Wave Loads on a Submerged Horizontal Box

This paper is concerned with calculations of the two-dimensional nonlinear vertical and horizontal forces and overturning moment due to the unsteady flow of an inviscid, incompressible fluid over a fully-submerged horizontal, fixed box. The problem is approached on the basis of the Level I Green-Naghdi (GN) theory of shallow-water waves. The main objective of this paper is to present a comparison of the solitary and cnoidal wave loads calculated by use of the GN equations, with those computed by Euler’s equations and the recent laboratory measurements, and also with a linear solution of the problem for small-amplitude waves. The results show a remarkable similarity between the GN and Euler’s models and the laboratory measurements. In particular, the calculations predict that the thickness of the box has no effect on the vertical forces and only a slight influence on the two-dimensional horizontal positive force. The calculations also predict that viscosity of the fluid has a small effect on these loads. The results have applications to various physical problems such as wave forces on submerged coastal bridges and submerged breakwaters.Copyright

Solitary and cnoidal wave scattering by a submerged horizontal plate in shallow water

Solitary and cnoidal wave transformation over a submerged, fixed, horizontal rigid plate is studied by use of the nonlinear, shallow-water Level I Green-Naghdi (GN) equations. Reflection and transmission coefficients are defined for cnoidal and solitary waves to quantify the nonlinear wave scattering. Results of the GN equations are compared with the laboratory experiments and other theoretical solutions for linear and nonlinear waves in intermediate and deep waters. The GN equations are then used to study the nonlinear wave scattering by a plate in shallow water. It is shown that in deep and intermediate depths, the wave-scattering varies nonlinearly by both the wavelength over the plate length ratio, and the submergence depth. In shallow water, however, and for long-waves, only the submergence depth appear to play a significant role on wave scattering. It is possible to define the plate submergence depth and length such that certain wave conditions are optimized above, below, or downwave of the plate fo...

Laminar flow around sharp and curved objects: the lattice Boltzmann method

The lattice Boltzmann method (LBM) is a relatively new computational method to model fluid flows by tracking collision, advection, and propagation of mesoscopic fluid particles. LBM originated from the cellular automata combined with kinetic theory and the Boltzmann equation. The method is used to solve the explicit finite-difference scheme lattice Boltzmann equations which are second order in space and first order in time. LBM does not attempt to solve the Navier–Stokes equations directly; however, it obeys the equations. The two-dimensional flows around square and circular cylinders are simulated with uniform and nonuniform grid structures using the LBM. The boundary layer growth and wake region physics are captured with small-scale details, and the results are validated by comparison with laboratory experiments for the Reynolds numbers between 50 and 350. Compatibility of the method in simulating flow around hydrofoil geometries and a combination of objects is also provided.

Boundary Layer and Wake Region Simulation for Low Reynolds Number Flows Around Bluff Bodies Using the Lattice Boltzmann Method

Two and three-dimensional flows around solid boundaries are interesting and important subjects to both scientists and engineers. Lattice Boltzmann Method (LBM) is a relatively new computational method to simulate fluid flows by tracking the collision, advection and propagation of mesoscopic fluid particles. LBM is originated from the Cellular automata combined with kinetic theory and the Boltzmann equation. The method solves the explicit finite difference scheme lattice Boltzmann equations which are second order in space and first order in time. LBM does not attempt to solve the Navier-Stokes equations directly, however, it obeys them. The two-dimensional flows around square and circular cylinders are simulated with uniform and nonuniform grid structures using LBM. The boundary-layer growth and wake region physics are captured with small scale details, and the results are discussed in comparison with the available references for Reynolds numbers between 50 and 350. The compatibility of the method to simulate a flow around ship-shaped geometries and a combination of objects is also provided.Copyright