Offshore Airport Research Articles

On the Estimation Method of Hydrodynamic Forces Acting on a Huge Floating Structure (2nd Report)

A very large floating structure is now being considered as a possible candidate of an offshore airport. The structure is expected to be so large that the analysis of the hydrodynamic forces that will act on the structure by a conventional numerical technique is practically impossible because of the required huge computational burden. In order to overcome this difficulty, an approximate but quite accurate numerical method for the analysis of a diffraction problem was presented in the 1st report. The method exploits the fact that the structure is very large and assume a certain uniformity in the flow field around the structure except at the vicinity of the perimeters of the structure. The present paper extends the method to the analysis of a radiation problem (including that due to elastic motions) and shows that a similar approximate technique can be used in the analysis. In addition, as examples of the application of the presented method to some practical problems, an analysis of elastic responses of a very large floating structure in waves and an analysis of wave forces on a floating airport composed of two runway structures are carried out.

An alternative structural system for an offshore airport

An alternative floating system for an offshore airport and other reclamation works is presented. It consists of precast boxes filled with FRP hollow spheres which sit on pile system. A top slab system consisting of precast and cast in situ concrete slabs will make the whole system monolithic. The light weight but strong spheres will enable the system to make use the uplift force from water. The precast boxes and slab system will transfer the difference between the gravity and uplift forces, as well as any lateral forces to the pile system. Finally, a proposed method of any lateral forces to the pile system. construction is also presented.

Response Characteristics of a Long Life Type Floating Offshore Airport in Waves

Response Characteristics of a Long Life Type Floating Offshore Airport in Waves

COUNTERMEASURES FOR SETTLEMENT OF THE OFFSHORE AIRPORT

COUNTERMEASURES FOR SETTLEMENT OF THE OFFSHORE AIRPORT

On the Predictions of Hydroelastic Behaviours of a Huge Floating Structure in Waves

A huge box-shaped floating structure is now being proposed as one of the candidates of an offshore airport. According to the plan, the length and the width will be 5000 m and 1000 m respectively while the thickness of the structure is expected to be about 5 m. But, never in history has there existed such a structure, so we have many unknown factors about the behaviors of such structures in waves. Among them, one that is unique to such structures is large elastic deformations that will be induced by the dynamic effects of waves, because the horizontal dimension is extraordinary large compared to its thickness.Experiments on elastic deformations of such structures are quite difficult because, if both the horizontal and vertical dimensions are equally scaled, the resultant model should be as thin as less than 10 mm. Hence, the development of theoretical techniques to be able to predict elastic behaviors without experiments is quite important. For the structures considered in this study, the local displacements due to elastic deformations may be comparable to or even larger than the displacements due to rigid-body motions. Therefore in the predictions of hydrodynamic forces on the structure, the elastic deformations should be taken into account. On the other hand, the elastic deformations are in turn affected by the hydrodynamic forces. Thus the elastic deformations and the hydrodynamic forces interact with each other, which is called a hydroelastic interaction.The main purpose of this paper is to propose a new theoretical technique that can incorporate such hydroelastic interactions in the predictions of dynamic behaviours of a pontoon-type huge floating structure in waves. We compare the numerical results based on the presented theory with experimental data, which are obtained by making use of a flexible model in a water tank and discuss the effectiveness of our theory.

Response Characteristics of a Long Life Type Floating Offshore Airport in Waves

Response Characteristics of a Long Life Type Floating Offshore Airport in Waves

Response Characteristics of a Long Life Type Floating Offshore Airport in Waves

In the first report, the basic concept of a longlife-oriented new type floating offshore airport was proposed and its fundamental response characteristics such as static stability, response due to an impact load were investigated. This second report deals with the deflections and bending moments among waves with special considerations of its deck stiffness and effects of loss one unit due to replacing.The response to regular head waves are studied numerically and verified by experiments. The hydrodynamic forces induced by wave are calculated by using 3D singularity distribution method taking the symmetry of structure into accounts. On the other hand, the structural analysis is conducted by using the application of FEM approach. Then, the hydroelastic responses, namely deflection and bending moment in waves are determined by combining the above two analyses.The influence of deck stiffness on deflection and moment are discussed through a series calculations. Also the loss of unit in replacing condition is investigated, and some suggestions for such type floating airport are proposed consequently.

Approach to the Off-shore Urban Airport-Case of the Kansai International Airport

The Kansai International Airport is the full-scale, large off-shore airport, the first of its kind in the world. This paper presents, first, the analyses of the Kansai International Airport in terms of its planning and technology. It also proposes the concept of the off-shore urban airport which might effectively become the main stream of the future airport construction project in this country. Technical reports on major works of the construction of the Kansai International Airport are also included.

Predictions of Air Pollution from an Offshore Airport (IV)

Predictions of Air Pollution from an Offshore Airport (IV)

Noise levels of Hong Kong marine craft

Noise measurements were made of jetfoils, hydrofoils, hovercraft, and nine other kinds of passenger and commercial marine craft operating in Hong Kong's Victoria Harbor for the purpose of predicting noise impacts expected from similar craft at a proposed offshore airport. Tape recordings of several passbys of each craft were analyzed to obtain characteristic time histories, spectra, and maximum, statistical, and equivalent noise levels. Results provide initial indication of main concerns expected from marine craft noise and suggest operational abatement measures which may be effective. [Work supported by the Hong Kong Civil Aviation Department.]

浮体工法による海上空港

浮体工法による海上空港

Discussions of “Dolosse Armoring Design for an Offshore Airport”

Discussions of “Dolosse Armoring Design for an Offshore Airport”

Wave Exciting Forces on Groups of Floating Bodies

A floating offshore airport, a floating offshore city, etc. are giant marine structures supported by a great number of floating bodies as never been experienced in the past. Because of limitations in scale and ability of an experimental tank and a model, it very difficult to experimentally estimate the wave exciting forces and the drifting forces acting on these structures. It is necessary to establish a theoretical method for their accurate and practical estimation.For this purpose, we adopt, as a floating element, a semi-submersible circular dock with a cylinder type footing (Fig. 1) which will be actualized as a column of marine structures as mentioned above, and derive a theoretical formula from the velocity potentials for determining the wave exciting forces and the drifting forces acting on the floating elements which are arrayed in many rows and an infinite number of columns.In development of the theory, we divide a fluid domain into three parts, assume the velocity potentials in each part to be infinite series expansion of eigenfunction in each part, and take only the diverging waves interaction into account between rows and columns of floating element.A feature of this theoretical formula is that an interaction effect between rows can be explicity obtained.The numerical values obtained from this formula are in good agreement with those obtained by experiment.

Erratum for “Basic Considerations for Offshore Airport Construction”

Erratum for “Basic Considerations for Offshore Airport Construction”

Predictions of Air Pollution from an Offshore Airport

Predictions of Air Pollution from an Offshore Airport

Basic Considerations for Offshore Airport Construction

The basic considerations suggested for the construction of an offshore airport are: (1)Safe construction; (2)functional requirements; (3)operational efficiency; (4)convenience; (5)costs; (6)regional goals; (7)provisions for future; (8)state-of-the-art; and (9)acceptability. The construction plan which emerges as a result of the preceding basic considerations must include all those details that are required to produce a balanced, integrated, flexible, and economical offshore airport, in harmony with the environment. The marine platform and the access routes will require special considerations in the construction of an offshore airport. The major problems will be on account of the large-scale difficult and unprecedented construction over water, the logistics, and the pollution of the marine environment.

Offshore Airport Site Planning

Aspects of safety, cost, and environmental impact favor the use of landfill or polder sites at offshore locations in lakes or the ocean for airports. Studies for a number of large American and foreign cities at offshore sites have shown that adequate safety can be provided by conservative selection of design criteria. Costs for sites to suffice for a large metropolitan airport lie between $19,000 and $90,000/acre ($5 to $23 m²). Considering need for less land as buffer zone at offshore sites than at land-based airports, total site development costs are expected to lie between $230,000,000 and $900,000,000. Environmental effects are generally mild, but more research is needed in this area. The conduct and status of Chicago's airport studies are reviewed.

Erratum for “Trends in Offshore Airports”

Erratum for “Trends in Offshore Airports”

Geologic Effects of Cities: ABSTRACT

Human activities in an industrial society are geologically significant in coastal cities because of the amounts of sediment and wastes moved and resulting topographic changes. Small streams are altered or destroyed, many becoming sewers. Large streams are dredged to accommodate ocean-going vessels and nearby river banks are bulkheaded. Shallow areas (including wetlands) are filled to provide space for city growth. Sewer, industrial, and sediment discharges are deposited in navigation channels which eventually require extensive dredging and waste disposal operations. The volume of wastes, and the sediment yield per unit area of the city, equals or exceeds the discharge of many rivers. Dams and public water-supply systems change river flows and dredging can change tidal reg mes in the estuaries. Sand and gravel production and construction of groins, bulkheads, and other structures change ocean shorelines and disturb beach processes. In the future, human activities will extend to the continental shelf where sand and gravel deposits will be exploited, offshore electrical power plants will be built, and port facilities will be constructed for deep-draft vessels requiring extensive dredging across the shelf. Even offshore airport centers have been proposed. These urban processes and their geologic effects are well documented in the New York metropolitan region. End_of_Article - Last_Page 782------------

Trends in Offshore Airports

Searches for sites for major new airports near many large cities have been frustrated by lack of available land and a hostile reception from environmentalists. Because of this, airport siting has become one of the more complex and controversial areas of urban planning. Since many cities are situated near large bodies of water, they have investigated offshore construction projects to provide airport sites. Many water edge situated airports already exist. Environmental engineering studies at each of the eight offshore airport projects covered in this paper confirm that noise pollution zones can be almost completely sequestered over uninhabited water areas. Other studies have indicated that the environment around the offshore airport can be protected in terms of water quality, fish and wildlife, and natural water current patterns. Offshore airports can be built as landfill islands or peninsulas, dike and polder areas, pile supported decks, and floating platforms.