Abstract: A reinforcement butt stud welding method and a device therefore, capable of butt-welding a stud reinforcing bar coaxially to the end portion of a horizontally-laid existing reinforcement in a small work space; and a repairing/expanding method for a ferroconcrete structure. The reinforcement butt stud welding method includes the steps of fitting an earth clamp over the periphery of the end portion of the existing reinforcement, fitting an annular stud base that is a heat-resisting, insulating material to the conductor surface of the earth clamp by being pressed against the conductor surface, bringing the tip end of a stud reinforcing bar, loaded in a stud welding gun, into contact with the end face of the existing reinforcement, and keeping a ferrule disposed around the tip end portion of the stud reinforcing bar joined to the stud base to complete stud welding.

Abstract: A reinforcement butt stud welding method and a device therefore, capable of butt-welding a stud reinforcing bar coaxially to the end portion of a horizontally-laid existing reinforcement in a small work space; and a repairing/expanding method for a ferroconcrete structure. The reinforcement butt stud welding method comprises the steps of fitting an earth clamp over the periphery of the end portion of the existing reinforcement, fitting an annular stud base consisting of a heat-resisting, insulating material to the conductor surface of the earth clamp by being pressed against the conductor surface, bringing the tip end of a stud reinforcing bar, loaded in a stud welding gun, into contact with the end face of the existing reinforcement, and keeping a ferrule disposed around the tip end portion of the stud reinforcing bar joined to the stud base to complete stud welding.

Abstract: The present invention relates to a method of raising a structure while sustaining very large pressure due to same and then tmeporarily supporting the structure, and a wedge-type jack apparatus for use in the method. The wedge-type jack apparatus comprises a wedge-like drive member, an upper member and a lower member, these three members being disposed in a frame body such that the drive member is sandwiched between the upper and lower members in a laminated manner. A slide plate rests on the upper member. When the wedge-like drive member is pushed in a lengthwise direction, the upper member and the wedge-like drive member are moved up to raise the structure overlying the slide plate, while keeping the current condition unchanged. Upon the structure being raised up to a desired level, this level is maintained by stopper means which restricts movement of the wedge-like drive member. Thus, the wedge-type jack apparatus supports the structure while transmitting the load of the structure to a substructure.