FLOATABLE MEMBER, UNDERWATER/WATER SURFACE EXECUTION METHOD AND UNDERWATER/WATER SURFACE EXECUTION METHOD OF FORM TIMBERING

PROBLEM TO BE SOLVED: To facilitate the conveyance of steel materials or the carrying out of steel materials to be removed when a structure using steel materials is constructed in the water/on the water or when it is removed. SOLUTION: When a structure is constructed in and on the water, a floatable member 11 is used instead of a steel material. The floatable member 11 is constituted of a steel material 12 and buoyancy providing members 13 and 13. The steel material 12 is an H-shaped steel. The buoyancy providing members 13 are made of polystyrene resin, and they are arranged in a state to hold them between two flange plates 12b and 12b of the steel material 12. The buoyancy providing members 13 and steel material 12 are monolithically formed, and specific gravity of the floatable member 11 is capable of floating it on the water and seawater. The buoyancy providing members 13 are arranged in a state to store them between two flange plates 12b and 12b of the steel material 12. Accordingly, sectional area of the steel material 12 including also a space between two flange plates 12b and 12b of the steel material 12 is not so different from sectional area of the floatable member 11.