Comparison of Global Response of a 3-Span Floating Suspension Bridge With Different Floater Concepts

2016 ◽  
Author(s):  
Arnt G. Fredriksen ◽  
Basile Bonnemaire ◽  
Halvor Lie ◽  
Jan Munkeby ◽  
Anders Nesteby ◽  
...  
Keyword(s):  
Numerical Model ◽  
Structural Model ◽  
Wind Waves ◽  
Suspension Bridge ◽  
Point Of View ◽  
Irregular Waves ◽  
Floating Bridge ◽  
Bridge Crossing ◽  
Extreme Responses ◽  
Suspended Bridge

Several bridge concepts for crossing deep and wide fjords along E39 at the west coast of Norway have been developed the last years. One of the most challenging fjord crossing is suspected to be the crossing of Sulafjord, 3 to 5 km wide, 400 m deep and with presence of relatively large swell waves. A suspended floating bridge concept is a marine slender flexible structure with large volume elements as floating support. The hydrodynamic actions on the floaters is an additional excitation compared to a traditional suspended bridge with fixed piles. In order to assess the effects of this excitation, it is important to consider the whole system and accurate hydrodynamic methods. While the superstructure type — a suspended bridge — is set, the type of floating foundation remains open. From the offshore experience, it is seen that different types of floaters are used for moored platforms, and these floaters have significantly different characteristics in particular with regards to wave response and stability. The design requirements for an offshore platform differ greatly from those of a suspended floating bridge crossing a fjord. For a floating bridge, the payload requirements are not the most challenging, while it is more difficult to limit the tilting and dynamic excitation of the tower (mounted on the floaters). The bridge beam is suspended at the top of the towers and will respond to any excitation due to motions of the tower tops. A global numerical model of the bridge to simulate nonlinear dynamic response due to regular and irregular waves is built. The numerical model of the bridge is simplified from a structural point of view. However, the dynamical properties and eigenmodes are verified against a more detailed structural model. Together with a 50-year long continuous time-series of wind, wind waves and swells a study of the bridge operability and extreme responses for different floater concepts is conducted. Normally the design phase should aim at avoiding any natural periods to fall within the wave frequency domain. This seems difficult for the proposed 3-span floating suspension bridge, instead solutions to minimize the excitation from waves for wave periods around the given bridge eigenperiods are sought.

E39 Bjørnafjorden - floating bridge – challenges and solutions

2016 ◽  
Author(s):  
Sverre Wiborg ◽  
Tina Vejrum ◽  
Erik Sundet ◽  
Per Norum Larsen ◽  
Bernt Sørby ◽  
...  
Keyword(s):  
Mooring Lines ◽  
Curved Bridge ◽  
Floating Bridge ◽  
Bridge Crossing

The purpose of this paper is to investigate the main challenges and corresponding solutions for a floating bridge crossing Bjørnafjorden. The paper investigates challenges related to quantification of loads, design of permanent structures as well as temporary phases. The paper evaluates a curved bridge without mooring lines, but considerations are partly valid for a straight bridge anchored to the seabed as well. Both solutions have been used, but the length of the Bjørnafjorden crossing is significantly larger than previous bridges and thus more challenging.

Global Analysis of a Floating Wind Turbine Using an Aero-Hydro-Elastic Numerical Model: Part 2—Benchmark Study

2011 ◽  
Author(s):  
Neil Luxcey ◽  
Harald Ormberg ◽  
Elizabeth Passano
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Global Analysis ◽  
Weather Conditions ◽  
Irregular Waves ◽  
Benchmark Study ◽  
Floating Wind Turbine ◽  
Calm Water ◽  
Internal Forces ◽  
System Power

This paper describes and presents the results of a benchmark study of a floating wind turbine numerical model that includes aero- and hydro-elasticity. The modelled wind turbine is the NREL offshore 5 MW baseline wind turbine whose specifications are publicly available. The first part of this paper demonstrates the importance of including aeroelasticity and hydroelasticity in the system. Power production, internal forces and motion amplitudes are compared to results from models using a rigid tower and rigid blades. Comparisons are performed for different weather conditions such as calm water, regular and irregular waves, constant and varying wind. The consequences of including elasticity in the different parts of the model are studied. The second part of the paper presents a benchmark study against the codes of the Offshore Code Comparison Collaboration. The floater motions, blade and tower deflection and power generation are presented and discussed.

First Order Stochastic Lagrange Model for Asymmetric Ocean Waves

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Georg Lindgren ◽  
Sofia Åberg
Keyword(s):  
Numerical Algorithms ◽  
Wave Model ◽  
Ocean Waves ◽  
Point Of View ◽  
Irregular Waves ◽  
Linear Wave ◽  
Ocean Engineering ◽  
Vertical Movements ◽  
First Order ◽  
Water Conditions

The Gaussian linear wave model, which has been successfully used in ocean engineering for more than half a century, is well understood, and there exist both exact theory and efficient numerical algorithms for calculation of the statistical distribution of wave characteristics. It is well suited for moderate seastates and deep water conditions. One drawback, however, is its lack of realism under extreme or shallow water conditions, in particular, its symmetry. It produces waves, which are stochastically symmetric, both in the vertical and in the horizontal direction. From that point of view, the Lagrangian wave model, which describes the horizontal and vertical movements of individual water particles, is more realistic. Its stochastic properties are much less known and have not been studied until quite recently. This paper presents a version of the first order stochastic Lagrange model that is able to generate irregular waves with both crest-trough and front-back asymmetries.

Dynamic Modelling of a Spar Buoy Wind Turbine

2017 ◽  
Author(s):  
Giuseppe Roberto Tomasicchio ◽  
Alberto Maria Avossa ◽  
Luigia Riefolo ◽  
Francesco Ricciardelli ◽  
Elena Musci ◽  
...  
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Dynamic Modelling ◽  
Irregular Waves ◽  
Induced Response ◽  
Simulation Tool ◽  
Floating Structure ◽  
Mooring Lines ◽  
Wave Basin ◽  
Fast Wind

In the present paper, the dynamic response of a spar buoy wind turbine under different wind and wave conditions is discussed. Physical model tests were performed at the Danish Hydraulic Institute (DHI) off-shore wave basin within the EU-Hydralab IV Integrated Infrastructure Initiative. The OC3-Hywind spar buoy was taken as reference prototype. A spar buoy model, 1:40 Froude-scaled, was tested using long crested regular and irregular waves, orthogonal (0 degrees) and oblique (20 degrees) to the structure. Here the results concerning regular waves, with incidence orthogonal to the structure, are presented; the selected tests considered rotating and non-rotating blades. Measurements of displacements, rotations, accelerations, forces response of the floating structure and at the mooring lines were carried out. Based on the observed data, FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy’s (DOE’s), National Renewable Energy Laboratory (NREL), was calibrated and verified. The numerical model takes into account the wave induced response and the effects of the mooring lines on the overall system. The adopted spar buoy has three equally spaced mooring lines that were modelled as quasi-static taut or catenary lines through MAP++ (static module) and MoorDyn (dynamic module) in the FAST simulation tool. The tensions along the fairleads of the three mooring lines were examined. At the end of the calibration procedure, the numerical model was successfully used to simulate the dynamic motions of the floating wind turbine under combinations of wind and sea states for the selected wave attacks. All data from the DHI tests were converted to full scale using Froude scaling before being analyzed.

Mechanics of “Bumps” in Coal Mines: A Discussion of Violent Deformations in the Sides of Roadways in Coal Seams

1987 ◽  
Vol 40 (8) ◽  
pp. 1033-1043 ◽  
Author(s):  
Horst Lippmann
Keyword(s):  
Structural Model ◽  
Human Life ◽  
Coal Mines ◽  
Specific Property ◽  
Point Of View ◽  
Coal Seams ◽  
General Introduction ◽  
Recent Origin ◽  
Material Sciences ◽  
Physical Principles

Since long ago rock bursting has belonged to the most hazardous of events causing damage to material and loss of human life in underground cavities. Nevertheless, attempts to understand the physical principles of rock bursting from the point of view of the mechanical and material sciences seem to be of fairly recent origin. The following article deals especially with rock bursting in coal mines. After a general introduction, approaches based on a specific property of the excavated material called “proneness-to-bursting” are reviewed. This is followed by a survey of structural approaches to the problem. Finally, an elementary structural model is presented, leading to simple approximate conditions for the risk of initiating rock bursts, or for its efficiency.

Euler–Lagrange Two-Phase Model for Simulating Live-Bed Scour Beneath Marine Pipelines

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
A. Yeganeh-Bakhtiary ◽  
M. Zanganeh ◽  
E. Kazemi ◽  
L. Cheng ◽  
A. K. Abd Wahab
Keyword(s):  
Numerical Model ◽  
Granular Media ◽  
Fluid Shear Stress ◽  
Distinct Element ◽  
Fluid Phase ◽  
Point Of View ◽  
Two Dimensional ◽  
Two Phase ◽  
Drag Forces ◽  
Bed Scour

In this study, an Euler–Lagrange coupling two-phase flow model, namely movable bed simulator (MBS)-two-dimensional (2D) model was employed to explore the current-induced live-bed scour beneath marine pipelines. The fluid phase characteristics, such as velocity and pressure, were obtained by the Reynolds-averaged Navier–Stokes (RANS) equations with a k-ε turbulence closure model in a two-dimensional Eulerian grid, whereas the seabed beneath pipelines was traced as an assembly of discrete sand grains from the Lagrangian point of view. The live-bed scour was evolved as the motion of a granular media based on distinct element method (DEM) formulation, in which the frequent interparticle collision was described with a spring and dashpot system. The fluid flow was coupled to the sediment phase, considering the acting drag forces between. Comparison between the numerical result and experimental measurement confirms that the numerical model successfully estimates the bed profile and flow velocity field. It is evident that the fluid shear stress decreases with the increasing of gap ratio e/D. The numerical model provides a useful approach to improve mechanistic understanding of hydrodynamic and sediment transport in live-bed scour beneath a marine pipeline.

Semicrystalline Structure and Mechanical Properties of Polyolefin-Based Materials

2012 ◽  
Vol 441 ◽  
pp. 713-716
Author(s):  
Mizue Kuriyagawa ◽  
Koh Hei Nitta
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Draw Ratio ◽  
Structural Model ◽  
Point Of View ◽  
Cross Sectional ◽  
Molecular Weights ◽  
The Cross ◽  
Sectional Shape ◽  
Structural Point

The mechanical yielding and necking behaviors of metallocene-catalyzed high density polyethylenes were investigated from a structural point of view. In particular the natural draw ratio was investigated with different crosshead speeds, molecular weights, and the cross-section shapes of sample specimens. We proposed a structural model for explaining the necking formation in addition to the molecular weight and the cross-sectional shape dependences of the natural draw ratio.

scholarly journals Integrated Analysis of Terms from a Cognitive Point of View (Based on the Terminology of Photonic Crystals)

2020 ◽  
Vol 22 (3) ◽  
pp. 841-848
Author(s):  
V. O. Kuleshova
Keyword(s):  
Photonic Crystals ◽  
Semantic Analysis ◽  
Structural Model ◽  
Point Of View ◽  
Integrated Analysis ◽  
Cognitive Approach ◽  
General Terms ◽  
The World ◽  
Close Relationship ◽  
Definition Of

The article proposes a comprehensive methodology approach to terminological systems. The methodology involves several stages. The first one involves a semantic analysis. Then follows a structural model of the terminology in question based on the logical connections between objects and processes of a certain special field and their reflection in the professional language. Finally, the researcher discloses the pragmatic potential of terminology units and demonstrates their role in determining the position of the terminological system in the scientific view of the world. The research objective was to describe and apply this approach to the analysis of the terminology of photonic crystals. The study featured the terminology of photonic crystals. The terms were selected from several scientific books. The author employed the following methods: the method of semantic analysis, a cognitive approach to describing the structure of the terminology, and contextual analysis. The author revealed a close relationship between the internal form of the term and the sign. Understanding the internal form of the term makes it possible to determine the place of the term in the terminology, which guarantees it correct interpretation and use. The article introduces a convolved model of the terminological structure of photonic crystals and explains how the terms are organized within the terminological system and how the terminological system can be embedded in the scientific view of the world. The author highlighted the role of general terms in integrating terminological systems into the scientific view of the world and in the relationship between different terminological systems. The most accurate definition of the boundaries of the terminology is possible only in the context where the term can fully exercise its meaning.

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