The fluid impact forces on a bridge superstructure in horizontal and vertical directions due to tsunamis represented by solitary waves are investigated through a large-scale laboratory experiment and numerical simulations. The experiment is conducted in a two-dimensional wave basin using a 1:5 scaled reinforced concrete bridge deck model tested under...
Fluid-structure interaction (FSI) is a very interesting and challenging multi-disciplinary field involving interaction of a movable or deformable structure with an internal or surrounding fluid flow. FSI has several practical engineering applications such as the determination of the hydrodynamic forces on a structure or the dynamics of motion of bodies...
Fluid-structure interaction (FSI) is a very interesting and challenging multi-disciplinary field involving interaction of a movable or deformable structure with an internal or surrounding fluid flow. FSI plays a pivotal role in many different types of real-world situations and practical engineering applications involving large structural deformation and material or geometric...
An experiment on solitary wave impact on a vertical cylinder was conducted in the three-dimensional wave basin at the Oregon State University Hinsdale Wave Research Laboratory. The cylinder was designed using mechanic principles and finite element analysis techniques to enable accurate measurement of horizontal force and overturning moment. Video data...
Complex oscillations including chaotic motions have been identified in off-shore and submerged mooring systems characterized by nonlinear fluid-structure interactions and restoring forces. In this paper, a means of controlling these nonlinear oscillations is addressed. When applied, the controller is able to drive the system to periodic oscillations of arbitrary periodicity....
Stochastic analysis procedures have been recently applied to analyze nonlinear
dynamical systems. In this study, nonlinear responses, stochastic and/or chaotic, are
examined and interpreted from a probabilistic perspective. A multi-point-moored
ocean structural system under regular and irregular wave excitations is analytically
examined via a generalized stochastic Melnikov function and Markov...
The present research investigates nonlinear barge motions through analyses of coupled multi-degree-of-freedom (MDOF) deterministic and stochastic models. Roll-Heave-Sway and other lower-ordered models are developed to predict the nonlinear motions and analyze the stability of a class of ship-to-shore cargo barges. The governing equations of motion contain coupled rigid body Roll-Heave-Sway...
This dissertation examines tsunami and hurricane wave loads on bridge superstructures. Tsunamis have caused significant damage to coastal communities in recent years. For example, the 2011 Great East Japan Earthquake and resulting Tohoku Tsunami destroyed infrastructure along the east coast of Japan including bridge superstructures. Recent hurricanes have also caused...
The nonlinear response of an ocean system subjected to random excitations can exhibit very complex dynamic behaviors including jump phenomena and coexistence of attractors. In this study, the stochastic system response behavior of a simple (Duffing) oscillator under narrow-band random excitations is first examined in the subharmonic resonance region. A...
This investigation deals with the chaotic rocking response and overturning
stability of offshore equipment subjected to base excitations due to wave-induced
motions of the supporting compliant offshore structural system. The equipment
compliant structural system is modelled as a free-standing rigid object subjected
to horizontal and vertical base accelerations. Three of...
Response behavior of a nonlinear structural system subject to environmental loadings
is investigated in this study. The system contains a nonlinear restoring force due to large
geometric displacement. The external excitation is modeled as a narrowband stochastic
process possessing dynamic characteristics of typical environmental loadings.
A semi-analytical method is developed...
Recent developments in estimation of the survivability of a U.S. Navy transport barge in random seas are extended to improve accuracy. The single Degree-of-Freedom (DOF) model of a extreme roll response of a barge used in previous research is replaced by a 3-DOF roll-heave-sway model to include linear and nonlinear...
Fluid-structure interaction (FSI) is an interesting and challenging interdisciplinary area comprised of fields such as engineering- fluids/structures/solids, computational science, and mathematics. FSI has several practical engineering applications such as the design of coastal infrastructure (such as bridges, levees) subjected to harsh environments from natural forces such as tsunamis, storm surges,...
Infrastructures along the Oregon Coast are vulnerable to seismic events in the Cascadia Subduction Zone that could generate large tsunamis. Bridges along the coast are an important part of the transportation and lifeline system in the area. The major damages on these bridges due to earthquake and/or tsunami would result...
The (nonlinear) response behavior of a piecewise-linear system is investigated under
both deterministic and stochastic excitations in this study. A semi-analytical procedure is
developed to predict the system behavior by evaluating the joint probability density functions
of the Fokker-Planck equations of the stochastic piecewise-linear system under random
excitations via a...
This study presents a mooring analysis of the Ocean Sentinel buoy, which is a mobile test platform for Wave Energy Converters. The Ocean Sentinel is owned and operated by the Northwest National Marine Renewable Energy Center (NNMREC) at Oregon State University (OSU). The study involved a field observation as well...
The modeling and analysis of laboratory-generated nonlinear intermediate- to deep-water wave fields, using existing wavemaker theories and analysis tools, is one of the most challenging tasks in ocean science and engineering. On one hand, harmonics function (sine and cosine) -based wavemaker theories result in an inherent (linear) instability of the...
A Finite Element Model of a deployed Fiber-Optic Micro Cable (FOMC) was performed using the marine cable modeling software, OrcaFlex. The focus of this study was a parametric analysis of a two-part, towed cable array with the FOMC dragged behind a depressor and connected to a drogue chute. Length-to-diameter ratios...
This dissertation studies the coupled fluid-structure interaction (FSI) of a wave energy converter (WEC) and evaluates the design of a WEC mooring system. The research is conducted in support of conceptual development, field test and performance evaluation of WECs as part of the mission of the Northwest National Marine Renewable...
In this study, a coupled potential flow-viscous flow model is used for numerical wave tank simulation. The solver satisfies all the requirements for such a simulation environment. The coupling scheme is based on a non-overlapping heterogeneous domain decomposition method. In this method, the flow domain consists of two subdomains. In...
This thesis investigates the applicability of the finite element method to model wave energy converter (WEC) hydroelasticity using LS-DYNA. The proposed methodology uses the Arbitrary Lagrangian-Eulerian formulation to model Fluid-Structure Interaction (FSI) between the WEC and the fluid elements. This formulation allows for time-domain modeling of higher order effects such...
Complex nonlinear and chaotic responses have been recently observed in various
compliant ocean systems. These systems are characterized by a nonlinear mooring
restoring force and a coupled fluid-structure interaction exciting force. A general class
of ocean mooring system models is formulated by incorporating a variable mooring
configuration and the exact...
The reliability of ocean systems is dependent on organizational factors. It has been shown that low probability / high consequence system failures are overwhelmingly induced by organizational factors. However, no methodology is yet widely accepted for the evaluation of this phenomenon or its accurate quantification. A qualitative complementary approach is...
Base isolation is an alternative seismic design strategy in which the primary structures
and their internal components are uncoupled from the potentially damaging horizontal
components of an earthquake by base isolators which attenuate the transmission of
horizontal acceleration into the system. Rotating machines are among the key internal
components of...
With energy prices rising and increasing concern about the influence of fossil fuels on climate change, wave energy systems are on the verge of commercial implementation. These first generation wave energy converters utilize either pneumatics or hydraulics to convert the mechanical energy of waves into electricity. For the last several...
An optimization methodology, algorithms, and computer program for
cable/lumped-body deployment system are developed for the design and installation of
sonar packages in deep ocean ranges. In addition, a methodology and algorithms for the
control of the system are proposed.
A penalty function is developed in terms of the system parameters...
Biomechanical models have been used in designing human work environments to evaluate potential risks to workers before a work environment is constructed. In order for work environments to be modeled correctly, most biomechanical models require as input, an accurate body posture of the worker. This information can be obtained by,...
Engineering design projects are implemented to accomplish a variety of goals in organizations. As the complexity of each project grows, the risk and uncertainty accompanying each project increases as well. As a result project managers must identify potential risks to projects and create plans to avoid realized risks leading to...
Fluid-structure interaction (FSI) has been of significant research interest worldwide over the past several decades because of its variety of applications in both offshore and coastal engineering. Researchers analyzing FSI systems rely heavily on experimental tests in model scale in laboratories or large-scale sea trials. However, these tests are often...
Time-domain models were developed to predict the response of a tethered buoy
subject to hydrodynamic loadings. A coupled analysis of the interaction of a buoy and
its mooring is included and three-dimensional response is assumed. External loadings
include hydrodynamic forces, tethers tensions, wind loadings and the weight of both
cable...
The Horsetail Creek (HC) bridge is an example of an Oregon bridge that was classified as structurally deficient and was not designed to withstand earthquake (EQ) excitations. A fiber-reinforced polymer (FRP) rehabilitation was performed on the HC bridge to increase flexural and shear capacities for traffic loads. However, a seismic...
The absence of tsunami load provisions in coastal infrastructure design has led to unchecked resistance capacity of bridges against
one of the most eminent natural hazards on the U.S. west coast. The Spencer Creek Bridge, which was completely rebuilt on the Oregon coast in
2009, is a unique example to...
In view of the widespread damage to coastal bridges during recent tsunamis (2004 Indian Ocean and 2011 in Japan) large-scale hydrodynamic experiments of tsunami wave impact on a bridge with open girders were conducted in the Large Wave Flume at Oregon State University. The main objective was to decipher the...
A numerical study on the dynamic response of a generic rigid water-landing object (WLO) during water impact is presented in this paper. The effect of this impact is often prominent in the design phase of the re-entry project to determine the maximum force for material strength determination to ensure structural...
An experimental study of the dynamics of a generic rigid body during water impact and an equivalent-radius approximate analytical procedure is developed and calibrated in this study. The experimental tests in a wave basin covered a range of drop heights using a 1/6th-scale model of a practical water-landing object prototype...
This paper presents a parallel implementation and validation of an accurate and efficient three-dimensional computational model (3D numerical wave tank), based on fully nonlinear potential flow (FNPF) theory, and its extension to incorporate the motion of a laboratory snake piston wavemaker, as well as an absorbing beach, to simulate experiments...
A multidisciplinary perspective is necessitated for the analysis of wave energy conversion systems, spanning hydrodynamics, mechanics, electric power, and control systems. The complexity inherent in these scientific domains poses challenges for unified analysis. This paper addresses these challenges by connecting various domains through the application of circuit theory, characterizing the...
Radiation studies were performed on compound semiconductor heterostructure devices. The objective was to understand the degradation processes caused by the exposure of these devices to radiation. Preliminary experiments were focussed on studying the degradation phenomenon in single heterojunctions and single quantum wells. It was found that ionizing radiation like gamma...
This thesis is comprised of a manuscript based on a laboratory experiment run in the Tsunami Wave Basin as part of a research project funded by the Network for Earthquake Engineering Simulation called Housesmash. The purpose of the experiment was to better understand the role of the urban environment, represented...
Metal-plate-connected (MPC) trusses have traditionally been designed based on a
tributary load distribution and a simplified truss model. This design method ignores the
load-sharing and composite action in MPC roof truss systems, the semi-rigidity of MPC
joints, and joint eccentricity.
The main objective of this study was to provide a...
A numerical model for the simulation of fully-coupled fluid-structure
interaction is developed in this study. In modeling the fluid, the Reynolds
Averaged Navier-Stokes equations are solved for an incompressible viscous
fluid field and a k-ε model is employed for turbulence computations.
Hydrodynamic forces obtained by the integration of the fluid...
Wave energy converter research continues to advance and new developers are continuing to emerge, leading to the need for a general modeling methodology. This work attempts to outline the design methodology necessary to perform frequency domain analysis on a generic wave energy converter. A two-body point absorber representing a generic...
Concrete is certainly prone to internal deteriorations or defects during the construction and operating periods. Compared with other nondestructive techniques, infrared thermography can easily detect the subsurface delamination in a very short period of time, but accurately identifying its size and depth in concrete is a very challenging task. In...
A six degree of freedom (6DOF) point-absorber wave energy converter (WEC) called LUPA is being developed at Oregon State University. This research focused on analyzing a full- scale LUPA, called LUPA20, to answer the following questions: 1) How does a full-scale WEC perform due to various factors; 2) What are...
Knowledge of wave conditions in nearshore regions supports the development of
ocean wave energy technology by providing wave climatology for device design
considerations, and power output estimates. By modeling wave transformation
over the continental shelf, wave conditions were predicted in nearshore regions
where potential wave energy conversion sites are located....
Simulation models were developed to explore the reversible nature of gecko dry
adhesion system. The central idea of this model is that even with a small moment imparted on the contact tip, the seta can be easily ad-adhered. It is shown that this contact condition is very sensitive, but can...
This thesis is comprised of two manuscripts based on a laboratory experiment conducted to examine realistic wave forcing on a vertical wall subjected to tsunami loading. The first manuscript examined tsunami force and pressure distributions on a rigid wall that was fronted by a small seawall. Six different seawall heights...
This thesis presents the details of a large-scale laboratory experiment to study the runup velocity on a complex 3D bathymetry. The PIV measurements including the instrumental setup, the recording procedure, and the image processing are presented. Tsunami inundation directly affects the coastal population and is one of the most important...