A method for stiffening a sheet element is provided. The method includes a first step of providing stiffening modules each having a flange and at least one web. The stiffening modules are attached to the sheet element sequentially along a load path, where the stiffening modules are connected to each other via their respective flanges for a positive, frictional and/or materially bonded connection to form a stiffening structure, such that the stiffening modules have a combined effect, specifically stiffening and reinforcing the sheet element. A stiffening structure for a sheet element is also provided that has a plurality of stiffening modules arranged sequentially, and to a stiffening system that includes a stiffening structure and a sheet element.

A hull support structure of a liquefied gas tank has a foundation deck disposed around a liquefied gas tank; a skirt which supports the liquefied gas tank on the foundation deck; an inner bottom plate extending in a hull length direction, at a location that is below the liquefied gas tank; and a pair of bilge hopper plates each of which is provided between the foundation deck and corresponding one of both end portions of the inner bottom plate, wherein a plate connection section at which each of the pair of bilge hopper plates is connected to the foundation deck is disposed outward in a hull width direction, relative to a skirt connection section at which the skirt is connected to the foundation deck.

A method for stiffening a sheet element is provided. In this regard, the method preferably includes a first step of providing stiffening modules that have a flange and at least one web. Furthermore, the stiffening modules are preferably attached to the sheet element sequentially along a load path, the stiffening modules are connected to each other via their respective flanges using connecting means and/or joining methods for a positive, frictional and/or materially bonded connection to form a stiffening structure, such that the stiffening modules have a combined effect, specifically stiffening and reinforcing the sheet element. A stiffening structure for a sheet element is also provided that includes stiffening modules arranged sequentially, and to a stiffening system including a stiffening structure and a sheet element.

A frame may comprise a plurality of interlocking tab-and-slot frame members forming a three-dimensional structure. A removable stringer may be designed into one or more of the interlocking tab-and-slot frame members. The stringers may be removed after positioning and welding of tab-and slot frame members together. Notches may also be designed into and formed as additional features of a tab-and-slot frame member. Notches may serve as a guide for bending tab-and-slot frame members and in the creation of tabs and/or slots of the tab-and-slot frame members.

A frame may comprise a plurality of interlocking tab-and-slot frame members forming a three-dimensional structure. A removable stringer may be designed into one or more of the interlocking tab-and-slot frame members. The stringers may be removed after positioning and welding of tab-and slot frame members together. Notches may also be designed into and formed as additional features of a tab-and-slot frame member. Notches may serve as a guide for bending tab-and-slot frame members and in the creation of tabs and/or slots of the tab-and-slot frame members.

A hull support structure of a liquefied gas tank has a foundation deck disposed around a liquefied gas tank; a skirt which supports the liquefied gas tank on the foundation deck; an inner bottom plate extending in a hull length direction, at a location that is below the liquefied gas tank; and a pair of bilge hopper plates each of which is provided between the foundation deck and corresponding one of both end portions of the inner bottom plate, wherein a plate connection section at which each of the pair of bilge hopper plates is connected to the foundation deck is disposed outward in a hull width direction, relative to a skirt connection section at which the skirt is connected to the foundation deck.