This paper is to study the scattering problem and radiation problem between incident wave and a moored dual pontoon platform by using both a fully nonlinear numerical wave tank (NWT) and a physical tank. The nonlinear numerical wave tank is developed based on the velocity potential function and the boundary element method (BEM). In addition, a moored dual floating pontoon physical model is tested in an experimental wave tank to validate the numerical model for simulation of wave and structure interaction including mooring tension, structure translation and rotation. The phenomena of wave reflection and transmission due to a floating platform are also considered in the study. The experimential results indicate that the platform surge-RAO decays as the wave frequency increases. Similarly, the platform heave-RAO decays first until at the vicinity of the resonance frequency happening where the vertical amplitude rises up and then decays again. The tension-RAO has two resonance frequencies, the lower resonance is resulted by the surge montion, while the higer resonance is caused by the heave motion. Both wave reflection and transmission coefficients decrease near the heave resonance frequency. This indicates that the platform has the best performance in wave shelter effect at heave resonance to protect costal zone. In general, the comparisons of the numerical simulations and experimental results indicate the numerical horizontal motion have a good agreement, but for the vertical motion, the numerical predictions are larger than experiments especially near the heave resonance frequency. This may be due to the structure vertical velocity increases dramatically causing flow separation occurred below the structure sharp corner, thus the fluid viscous damping effect may play an important role in heave motion.

Thesis (Ph. D.)--Washington State University, 2002. / Title from PDF title page (viewed on May 26, 2005). Includes bibliographical references (p. 275-279).

This study is to develop a 2D fully nonlinear numerical wave tank used to investigate the wave-induced dynamic properties of a dual pontoon floating structure (DPFS) with a liquid container on the top. The nonlinear numerical wave tank, developed based on the velocity potential function and the boundary element method (BEM), is to simulate dynamic properties including sway, heave, roll, and tension response. In addition, a physical model of the dual floating pontoon is tested in a hydrodynamic wave tank to validate the numerical model for simulation of wave and structure interaction. In the numerical model, a boundary integral equation method (BIEM) with linear element scheme is applied to establish a 2D fully nonlinear numerical wave tank (NWT). The nonlinear free surface condition is treated by combining the Mixed Eulerian and Lagrangian method (MEL), the fourth-order Runge-Kutta method (RK4) and a cubic spline scheme. The second-order Stokes wave theory is used to generate the velocity flux on the input boundary. Numerical damping zones are deployed at both ends of the NWT to dissipate or absorb the transmitted and reflected waves. Acceleration potential method and modal decomposition method are adopted to solve the unsteady potential functions £X1,t and £X2,t, while the system of motion equation is established according to Newton's 2nd law. Finally, the RK4 is applied to predict the motion of the platform, and the variation of free surface. As for the hydrodynamic laboratory model test, an image process scheme is applied to trace the floating structure motion and the variation of water surface inside the sloshing tank, while the mooring tension is measured by a load cell and stored in a data logger. The comparisons of numerical simulations and experimental data indicate that the numerical predictions are larger than measurements especially near the resonance frequency. This discrepancy is probably due to the fluid viscous effect. To overcome this problem and maintain the calculation efficiency, an uncoupled damping coefficient obtained through a damping ratio (£a=C/Ccr=0.02) is incorporated into the vibration system. Results reveal that responses of body motion near the resonant frequencies of each mode have significantly reduced and close to the measurements. Therefore, the suitable value of the damping ratio for the floating platform is £a=0.02. Then the numerical model with a damping ratio is applied to investigate the dynamic properties of the floating platform for different arrangements, including different mooring angle, spring constant, spacing, and the liquid container. Results demonstrate that the resonant frequency of each mode, responses of body motion and mooring tensions change along with the settings. As a whole, the platform with smaller mooring angle, longer spacing between the pontoons, higher water depth and wider width of the liquid container has relatively stable body motions and less mooring tension. Finally, the comparisons of the effects of random and regular waves on the floating structure illustrate that the variation of water surface in the liquid container is much severe in random waves than in regular waves such that the interaction between liquid and floating structure is more chaotic and thus reduces the amplitude of each response mode. As a result, the mooring tensions for random waves become much gentler than the regular waves. Key words: Boundary integral equation method; fully nonlinear numerical wave tank; dual pontoon floating structure

Stockholm lider idag av omfattande bostadsbrist och ständigt ökande befolkningsmängd. För att möta detta ökande behov av bostäder i Stockholm finns en nödvändighet i att utforska nya vägar till att åstadkomma detta. Här finns en unik möjlighet till en förtätning av staden genom att utnyttja Stockholms stora vattenarealer för att bygga flytande bostäder. Som alternativ till den traditionella byggkonsten ämnar examensarbetet till att demonstrera de kvaliteter som finns med att bo på vatten genom att utforma ett attraktivt bostadsområde med flytande konstruktion. Projektet illustreras i det tidigare hamnområdet vid Liljeholmskajen i Årstadals hamn, Stockholm. För att åstadkomma detta utförs fallstudier på olika typer av flytande konstruktioner som finns på den svenska marknaden för att fastställa de bästa konstruktionslösningarna som leder till färdiga förslagshandlingar. Resultatet visar att ett flytande bostadsområde är genomförbart med dagens teknik som ett sätt att förtäta staden. Vidare utredningar måste dock göras för att i framtiden legalisera och förenkla lagstiftningen kring denna typ av boende. / Present day, Stockholm suffers from a significant lack of dwellings and the population in the county is ever increasing. To meet this escalating demand for residences it is essential to explore new paths of accomplishing this. Here lies a unique opportunity for densification of the city by taking advantage of Stockholm’s grand water areal to build floating residences. This essay aims to demonstrate an alternative to the traditional arts of building construction by presenting the qualities of living on water in a proposition for a floating residential area. The project is displayed as placed in an old industrial port - Liljeholmskajen - in Årstadal, Stockholm. To achieve this, case studies are made on different types of floating constructions on the Swedish market to establish the best constructional solutions, which have led to complete concept drawings. The result illustrates that a floating residential area is achievable with today’s technology as a method of dealing with the densification of cities. Further investigations are necessary to legalize and simplify the legislation of this type of living

Nowadays, the Norwegian Public Roads Administration plans to replace the ferry connections along the western coast of Norway with fixed road connections through the coastal highway E39 project. Due to the necessity of bridging long distances with considerable depths, non-conventional engineering solutions are being developed. To date, the first fjord planned to be cross is Bjørnafjord, located just in the middle of Trondheim and Kristiansand. In order to bridge the fjord distance, three innovative solutions have been developed: a submerged floating tube bridge, a floating pontoon bridge, and finally, a multi-span suspension bridge. It is known that these structures are affected by periodic environmental forces which may cause significant fatigue problems in some structural components, disturbing their service behaviour. The aim of this master thesis is to deeply analyse the cumulative fatigue damage produced in the mooring lines of a proposed solution for crossing Bjørnafjorden as well as to investigate the influence of the implementation of different mooring line scenarios on the damage. A 3D finite element model of the chosen alternative was conducted and verified. The model provided the stress variations in each mooring line which were processed through Excel software using macros performed as well as Matlab scripts in order to obtain the results. Then, a deep fatigue damage assessment was carried out discussing how different tension-history time period calculations affect to the damage, as well as which fatigue evaluation methodology is adequate for the chosen solution. Moreover, the fatigue damage produced on the initial mooring line system configuration was analysed. It was investigated the repercussions of each direction and the contribution of each environmental load on the total damage. Last but not least, it was researched the influence of different water depths and line configurations on the fatigue damage. The results show that the fatigue damage obtained for the adopted solution remains far from the failure threshold with the worst damage produced in the mooring line chain components. The previous results have been computed employing a 1-hour analysis duration through the rainflow counting method. Also, the worst fatigue damage is produced by environmental states propagating in a westerly direction, corresponding to the maximum fetch. Regarding the load contribution in the fatigue damage, it is proved in this case that the current loads stabilise the mooring lines, reducing the fatigue damage. Finally, investigating the effect of various mooring line scenarios on the damage it has been proved that the fatigue damage is increased as the water depth is decreased and as the lateral mooring lines are separated from the initial configuration.

Made available in DSpace on 2016-08-18T18:55:16Z (GMT). No. of bitstreams: 1 Dissertacao Ernane.pdf: 343643 bytes, checksum: 8b8b5c4c5ea63864317f2e111388dad7 (MD5) Previous issue date: 2013-04-25 / This disertation deals with as the research object, the process of deploying of Pontão de Cultura do Tambor de Crioula de São Luís do Maranhão. This Pontão stems from a policy developed by the Ministry of Culture (MinC). In this sense, the research covers both the intangible aspect, in order to analyze the factors, cultural or otherwise, that contribute and / or hinder the implementation of this policy as well as the tangible, referring to the Casa do Pontão de Cultura, which is located in a townhouse in historic Praia Grande, in the Historic Centre of São Luís. For the research subjects were considered, such as leaders of groups of Tambor de Crioula; researchers to develop studies on the subject, representatives of cultural institutions and bodies that are directly and indirectly involved with the deployment of Pontão de Cultura do Tambor de Crioula in São Luis. This last group stand out representatives of the Institute of Historical and Artistic Heritage (IPHAN), the Ministry of Culture (Secma); Municipal Foundation of Culture (FUNC), as well as Tambor de Crioula associations of existing barrel. The investigation was conducted from the perspective of interpretive culture of Antonio Gramsci and the dialectical materialism of Karl Marx, articulated the analytical categories proposed by Clifford Geertz, Néstor García Canclini and Ozanira Maria da Silva and Silva. / Esta dissertação aborda, como objeto de investigação, o processo de implantação do Pontão de Cultura do Tambor de Crioula em São Luís do Maranhão. Este Pontão origina-se de uma política desenvolvida pelo Ministério da Cultura (MinC). Neste sentido, a pesquisa abrange tanto o aspecto intangível, no sentido de analisar os fatores, culturais ou não, que contribuem e/ou dificultam a implementação dessa política, bem como o tangível, referente à Casa do Pontão de Cultura, que se localiza em um casarão histórico na Praia Grande, Centro Histórico de São Luís. Para a pesquisa foram considerados sujeitos, tais como lideranças de grupos de Tambor de Crioula; pesquisadores que desenvolvam trabalhos sobre o tema; representantes de instituições e órgãos culturais que estejam envolvidos direta e indiretamente com a implantação do Pontão de Cultura do Tambor de Crioula em São Luís. Deste último grupo destacam-se representantes do Instituto de Patrimônio Histórico e Artístico Nacional (IPHAN); da Secretaria de Estado da Cultura (SECMA); da Fundação Municipal de Cultura (FUNC), bem como das associações de Tambor de Crioula existentes. A investigação foi conduzida com base na perspectiva interpretativa de cultura de Antonio Gramsci e no materialismo dialético de Karl Marx, articulada às categorias analíticas propostas por Clifford Geertz, Néstor Garcia Canclini e Maria Ozanira da Silva e Silva.

Today, there is a significant demand for electricity, a demand expected to increase in the coming years. To meet market needs, the number of offshore wind turbines is increasing, along with their dimensions to generate a greater amount of electricity. This leads to anecessity for a new generation of freight ships with bigger dimensions and capacity for transportation and installation of wind turbine components. Finite Element models enable comprehensive analyses of the hull beams' components, bulkheads, and supports, providing relevant information about the hull's stress impact for different load combinations. The advantage of creating a model is to provide a clear overview while allowing the product to be simulated before production, facilitating a better understanding of the product's future function and appearance. A Finite Element model's analysis results largely reflect reality and thus constitute a valuable tool for ship production. In SAP2000, a shell model was created over a pontoon with interconnected beam and shell elements. The model was simulated with loads from self-weight combined with hydrostatic pressure in combination with various sets of hull components. Four simulations were performed with analyses of shell and frame stresses, showing that a stronger construction results in less stress variation in the pontoon's constituent elements. The upper side of the pontoon did not meet the tolerance values of ±50 MPa for either frame or shell elements in the first analysis. When the frame dimensions were increased, the shell elements met the stress level criteria, but the frame elements still significantly exceeded the tolerance values. An increased plate thickness was not beneficial for the structure’s stress load as the self-weight increased without providing additional stiffness.