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 multistage wedge-shaped jack apparatus is provided for jacking up and maintaining a heavy structure for mounting and replacing bearing units interposed between the heavy structure and a lower base while considerably increasing the jack amount without increasing the overall length of the apparatus. A wedge-shaped drive member (1) and a wedge-shaped pressure receiving member (2) are laminated on a base plate (3) and brought into contact with each other with the respective slant surfaces (11) and (21). A push/pull drive device (6) is provided in cooperation with a reactive force receiving device (5) for limiting a movement of the wedge-shaped pressure receiving member. A single or a plurality of auxiliary wedge-shaped members (7) are provided to the wedge-shaped drive member to be detachably coupled with each other in order.

Abstract: A method of raising/supporting a bridge or the like on a lower structure involving sliding an upper wedge-shaped pressure receiving member having a slope on its lower face and a wedge-shaped drive member having a slope on its upper face relative to each other on their slopes by drive mechanism for driving the wedge-shaped drive member, to raise the upper face of the upper wedge-shaped pressure receiving member with respect to the lower structure. The method further involves regulating the upper wedge-shaped pressure receiving member and the wedge-shaped drive member from their relative movements after the bridge has been raised. The method further involves removing the drive member after the regulation of the relative movements of the upper wedge-shaped pressure receiving member and the wedge-shaped drive member.

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.