Abstract: A method of forming stiffened plate by welding a plurality of stiffener materials and a steel plate, so that closed cross-sectional structures are secured onto a surface of the steel plate. The stiffener materials are joined to the steel plate as a result of edge portions of the stiffener materials which are in contact with the steel plate by being laser welded at a predetermined welding speed as a result of a laser having a predetermined output being irradiated from a predetermined direction thereon from the external side of the closed cross-sectional structures. Accordingly, it is possible to achieve an improvement in the weld quality when welding stiffener materials onto a steel plate, and to achieve an improvement in fatigue strength.

Abstract: A method of forming stiffened plate by welding a plurality of stiffener materials and a steel plate, so that closed cross-sectional structures are secured onto a surface of the steel plate. The stiffener materials are joined to the steel plate as a result of edge portions of the stiffener materials which are in contact with the steel plate by being laser welded at a predetermined welding speed as a result of a laser having a predetermined output being irradiated from a predetermined direction thereon from the external side of the closed cross-sectional structures. Accordingly, it is possible to achieve an improvement in the weld quality when welding stiffener materials onto a steel plate, and to achieve an improvement in fatigue strength.

Abstract: A welded joint improved in fatigue strength, a steel deck using the welded joint, and a process of producing the steel deck are provided. A steel deck 3 includes a steel plate 10 having a paving surface 11 on which a pavement is placed, and stiffeners 20 welded to a lower surface 12 of the steel plate opposite the paving surface. Single bevel grooves 22 are formed at respective edges 21 of each stiffener brought into contact with the steel plate, and a weld metal 30 is deposited in each single bevel groove 22. The weld metal is a low transformation-temperature welding material whose martensitic transformation occurs in a predetermined low temperature range. The groove angle ? of the single bevel grooves 22 and welding conditions are set based on data acquired so as to obtain a fixed dilution ratio of the weld metal 30 through control of penetration rate.

Abstract: A stiffened plate is formed by welding a plurality of stiffener materials which, together with a steel plate, form closed cross-sectional structures onto a surface of the steel plate. The stiffener materials are joined to the steel plate as a result of edge portions of the stiffener materials which are in contact with the steel plate by being laser welded at a predetermined welding speed as a result of a laser having a predetermined output being irradiated from a predetermined direction thereon from the external side of the closed cross-sectional structures. Accordingly, it is possible to achieve an improvement in the weld quality when welding stiffener materials onto a steel plate, and to achieve an improvement in fatigue strength.