Abstract: The Removable Bottom Founded Structure (RBFS) is an offshore platform for petroleum drilling and producing operations intended for deployment in waters with severe weather and iceberg conditions. The structure is normally held down by gravity, but during the deballasting procedure a hold-down system is employed to keep the platform on the subbase until site evacuation. The system that is used to hold the platform down onto the subbase is located where the platform meets the subbase. It operates on the principle of hydrostatics. On the underside of the columns there are elastomeric seals that define chambers between the column and the subbase which may be evacuated by pumping. Pressure by the platform weight forces the elastomeric seals down onto the subbase to create a fluid-tight seal so that no seawater will enter the evacuated chambers. The reduction of the buoyancy forces will hold the platform onto the subbase until such time as the platform is totally deballasted.

Abstract: A structure having a polygonal base and sloping sides forming a frustrum includes a load bearing outer skin which contains an inner assembly and an outer assembly. Both the inner and outer assemblies include a skin plate member which is stiffened by stiffeners welded to one side of the skin plate member. The stiffeners are located at spaced intervals from each other and are disposed substantially perpendicular to the skin plate member. The inner and outer assembly are placed substantially parallel to each other to form a composite structure having an internal cavity defined by the inner and outer plates. The stiffeners of the inner assembly and the outer assembly are disposed in the cavity at a spaced relation to each other and extend partly into the cavity. A cementitious material substantially fills the cavity thereby completing the load bearing outer skin structure. The stiffeners may be flat steel plates or may have the profile of structural shapes such as angles or T's among others.

Abstract: The load bearing outer skin contains an inner assembly and an outer assembly. Both the inner and outer assemblies include a skin plate member which is stiffened by stiffeners welded to one side of the skin plate member. The stiffeners are located at spaced intervals from each other and are disposed substantially perpendicular to the skin plate member. The inner and outer assembly are placed substantially parallel to each other to form a composite structure having an internal cavity defined by the inner and outer plates. The stiffeners of the inner assembly and the outer assembly are disposed in the cavity at a spaced relation to each other and extend partly into the cavity. A cementitious material substantially fills the cavity thereby completing the load bearing outer skin structure. The stiffeners may be flat steel plates or may have the profile of structural shapes such as angles or T's among others.

Abstract: A marine structure comprising a cellular caisson which forms a stable platform for carrying out a variety of offshore operations in the arctic and sub-arctic regions is provided. The structure may be grounded on reasonably level sea bottom with a minimum of sea bed preparation in shallow water or mounted upon a previously prepared berm. Resistance to local ice forces is provided by the hexagonal cellular arrangement of the perimeter and interior walls which make up the cellular caisson. Global foundation resistance is obtained by introducing a suitable quantity of ballast into the structure. The design allows clusters of two or more structures to be grouped together to augment the offshore installation and to permit the offshore installation to be developed in stages at the site.