Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
CFD Modeling And Analysis of an Open Quay Wall
Tsolaridou, Anastasia (Department of Civil Engineering, Aristotle University of Thessaloniki) | Angelides, Demos C. (Department of Civil Engineering, Aristotle University of Thessaloniki)
ABSTRACT In this paper, the numerical investigation of a high deck open quay wall structure, supported on piles partially embedded in a porous embankment is presented. The governing equations solved are the Reynolds Averaged Navier-Stokes (RANS) equations of motion, while the two equation RNG turbulence transport model is applied. Parametric studies have been carried out for two different wave lengths, two structure clearances and two inclinations of the porous embankment. The forces exerted on the piles and on the underside of the deck of the quay structure due to waves are computed. The forces exerted on a single cylindrical pile computed with the present numerical model are compared with those calculated through the analytical equation of Morison. The computed pressures on a deck structure are compared with the experimental results of the investigation of other researchers. INTRODUCTION Quay walls are marine structures, generally parallel to the shore. They are broadly classified into two main types, quays with solid (closed) construction, like sheet and gravity walls with a solid vertical berthing face, and quays with an open construction, having a suspended deck supported on piles (British Standard's Institution, 1988). The type of the open quay construction is not in common use worldwide. However, in cases where there is need for wave absorption or there are favorable ground conditions, the open quay is preferable against the solid one (PIANC, 1997). The presence of the porous rubble slope in the structure of the open quay is responsible for the wave energy absorption and the reduction of the wave reflection. Furthermore, in ports with poor near surface soils but with good end bearing capacity for piles, an open pile supported quay would be most economical (Department of Defense, 2005). However, an open structure is proved to be more delicate than a solid one.
- Government > Regional Government > North America Government > United States Government (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Military > Army (0.94)
Risk In Performance of a Free Floating Structure Subjected to Combination of Wave Frequencies
Diamantoulaki, Ioanna (Department of Civil Engineering, Aristotle University of Thessaloniki) | Angelides, Demos C. (Department of Civil Engineering, Aristotle University of Thessaloniki)
ABSTRACT: The risk of failing to achieve the acceptable performance (performance risk) of a free floating structure under the combined action of various wave frequencies is investigated in the frequency domain. Here, performance is quantified in terms of no exceedance of a threshold for the response level corresponding to each degree of freedom. Quantification of the performance risk is based on a Monte Carlo simulation technique. The numerical analysis of the free floating structure is carried out using a three dimensional hydrodynamic analysis. Several cases of different combinations of wave frequencies are investigated. The second-order hydrodynamic interactions of pertinent wave frequencies are considered in the analysis for each combination examined. Two issues are investigated, namely:performance and performance risk for the free floating structure considered. The performance and risk levels of the second-order solution are compared with the results of the corresponding first-order solution in order to investigate the significance of second-order quantities in the assessment of both performance and performance risk levels. According to the results generated by the present study, secondorder wave effects can generally strongly affect performance and performance risk levels. INTRODUCTION Considering the case of a free floating body subjected to the simultaneous action of two or more wave frequencies, non-linear hydrodynamic analysis needs to be carried since second-order wave effects can highly affect the response of the free floating body. This happens because several effects can hardly be predicted when using linear (first-order) theory, such as wave drifting and interaction between wave trains of different frequencies (Murao, 1960; Newman, 1990 and 2004 and McIver, 1992). For this reason, plenty of investigations, relevant to the analysis and computation of second-order wave effects have been carried out including among others Kosmeyer et al. (1988), Lee (1991) and Kim M.H. (1992 and 1993).
- Europe (1.00)
- North America > United States (0.28)
- Asia > Japan (0.28)
Fatigue Analysis of a Tripod Supporting Structure of an Offshore Wind Turbine
Zacharioudaki-Apelidou, Fotini (Department of Civil Engineering, Aristotle University of Thessaloniki) | Dedonakis, Fotios (Department of Civil Engineering, Aristotle University of Thessaloniki) | Angelides, Demos C. (Department of Civil Engineering, Aristotle University of Thessaloniki)
ABSTRACT Offshore Wind Turbines (OWT) are exposed to loads varying both in time and in amplitude, designating fatigue damage as a main concern. In this paper, an analysis is presented for assessing the total fatigue damage of an OWT tripod supporting structure. The combined effect of wind and wave loading is computed and different loading scenarios are examined to determine the dominating load on the final result. Further investigation is done to assess the influence of different welding profiles of the tubular joints of the structure on the final fatigue resistance. Results are presented and conclusions are drawn, indicating the importance of the combined analysis. INTRODUCTION The geography of Greece consists of numerous inhabited smaller and bigger islands, with energy needs varying throughout the year. This decentralized demand for energy can be addressed by providing the islands with an autonomous source of energy production. Offshore Wind Turbines (OWT) are an appealing alternative to satisfy this need. A solution like this would allow the islands to use their own resources and produce their own energy in an environmentally friendly way. The realization of OWT is a complicated task and an engineering challenge. Several design scenarios have to be taken into account, including extreme load and fatigue load cases. OWT are exposed to critical environmental loads, which designate this kind of analysis essential. Contrary to common offshore structures- such as oil and gas platforms, OWT are not only exposed to dynamic wave loads but also to dynamic loads from the turning rotor of the Wind Turbine. These loads make OWT susceptible to fatigue damage. Loads varying in amplitude, direction and time act on the structure throughout its lifetime, progressively reducing the fatigue resistance. Deeper water depths for installation and turbines of larger size used nowadays, lead to increased loadings upon the supporting structure.
- Europe (1.00)
- North America > United States (0.69)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems > Platform design (0.92)
- Facilities Design, Construction and Operation > Facilities and Construction Project Management > Offshore projects planning and execution (0.82)
- Health, Safety, Environment & Sustainability > Environment (0.67)