Vessel structures and structures in marine vessels

Layered structure for use in marine vessels, such as ships, floating platforms etc, comprising two substantially parallel metal sheets with a concrete layer in between, where the concrete has weight of less than for normal concrete, and less than 1200 kg/m3, where the layered structure is dimensioned as if the concrete layer in the structure carries essentially no tension but is carrying most compressive forces and support the metal sheets.

Marine vessel or layered structure in accordance with one of the proceeding claims, wherein the concrete layer comprises a plurality of longitudinal substantially parallel load carrying channel elements with equal or different cross sections and with an internal void, which may, together with other elements in the layered structure, form spar-boxes.

Marine vessel or layered structure in accordance with one of the preceding claims, wherein one or both of the surfaces of the metal sheets faced away from the concrete layer or the inside of a spar-box may include another outer layer of a different material.

Method for improving carrying capacity of existing structures, with the following steps:

• attaching at least one other plate element to the existing structure to form a void,
• filling the void with concrete with density significantly less than that of normal concrete, and less than about 1200 kg/m3 to the void, and
• letting the concrete cure.

Improved corrugated structure with alternating mainly parallel ridges and grooves, wherein it comprises on one or both sides at least one plate element, attached to the corrugates plate so that the plate element covers at least one groove and forms a void, which void is filled with a concrete with a density significantly less than that of normal concrete, and less than about 1200 kg/m3, where the layered structure is dimensioned as if the concrete layer in the structure carries essentially no tension but is carrying most compressive forces and support the metal sheets.