To provide a high-rise horizontal member jack-down method which jacks down a high-rise horizontal member to the height of a bearing portion on a column by alternately holding the high-rise horizontal member by jack 2 groups which are each formed by piling up small jack link groups with safety nuts in multiple stages, and gradually lowering the height of the small jack link groups when out of the bearing, and to provide a jack to be used for the method.
According to the jack-down method, the two jack 2 groups 2A, 2B are formed by piling up the small jack link groups 3' with the safety nuts on the column 1 in multiple stages, and the jack groups then function as a conventional stand saddle, a temporary bearing saddle, and a lowering jack. The jacks 2 of the first and second groups 2A, 2B are alternately lowered or elevated, and the jack 2 is removed beginning from the small jack link group 3' in an upper stage at the time of jack-down operation, while the jack bears the high-rise horizontal member at the time of jack-up operation. Thus by repeatedly carrying out the jack-down and jack-up operations, the high-rise horizontal member is lowered to the bearing portion 5 on the column 1, and then the high-rise horizontal member is borne by the bearing portion 5.
Mitsuo Chonan
Ishiwatari Eibo