Method for Assembling Braces by Casting in an Offshore Support Structure for a Wind Turbine

A method for assembling an offshore support structure for a wind turbine, the method comprising:

• providing a tower support for carrying a wind turbine tower;
• providing N first braces and N second braces, wherein N is an integer having a value of at least three, each brace having a first end part and a second end part;
• wherein each of the braces has a longitudinal central axis;
• for each pair of one of the first braces and one of the second braces, connecting the second end part of the first brace to a first part of the tower support at a first connection, connecting the second end part of the second brace to a second part of the tower support at a second connection, and connecting the first end part of the second brace to the first brace at a third connection, wherein the second part of the tower support and the second connection are above the first part of the tower support and the first connection when the support structure is oriented for offshore operation, and wherein the tower support, the first brace, and the second brace form a triangle in a vertical plane, and wherein the N pairs of braces are directed outwards from the tower support in different directions about a vertical central axis of the tower support;
• wherein the method comprises at least one of A, B and C:
• (A) providing the first connection with a wall-opening in the first part of the tower support and a sleeve with a first sleeve-end and a second sleeve-end, wherein the first sleeve-end is welded to a rim of the opening and wherein the sleeve extends from the rim inwards into an inner volume of the first part of the tower support, and wherein the sleeve extends no more than 0.2 m outwards from the rim;
• inserting the second end part of the first brace through the opening into the sleeve;
• filling casting material into a volume between the sleeve and the first brace;
• and
• solidifying the casting material for rigidly fixing the first brace in the sleeve;
• (B) providing the second connection with a wall-opening in the second part of the tower support and a sleeve with a first sleeve-end and a second sleeve-end, wherein the first sleeve-end is welded to a rim of the opening and wherein the sleeve extends from the rim inwards into an inner volume of the second part of the tower support, and wherein the sleeve extends no more than 0.2 m outwards from the rim;
• inserting the second end part of the second brace through the opening into the sleeve;
• filling casting material into a volume between the sleeve and the second brace;
• and
• solidifying the casting material for rigidly fixing the second brace in the sleeve;
• (C) providing the third connection with an opening in a wall of the first brace and a sleeve with a first sleeve-end and a second sleeve-end, wherein the first sleeve-end is welded to a rim of the opening and wherein the sleeve extends from the rim inwards into an inner volume of the first brace, and wherein the sleeve extends no more than 0.2 m outwards from the rim;
• inserting the first end part of the second brace through the opening into the sleeve;
• filling casting material into a volume between the sleeve and the second brace;
• and
• solidifying the casting material for rigidly fixing the second brace in the sleeve.