| 摘要 |
PROBLEM TO BE SOLVED: To safely construct a comparatively small steel tower in a narrow place of streets or a mountain district. SOLUTION: A base mast 12 is disposed on the side of a steel tower 1 in the process of construction, the base mast 12 is supported on the steel tower 1 using a first mast holder 35, and the middle part of a mast 21 elongated upward from the base mast 12 is supported on the steel tower 1 using second mast holders 51, 51. Thus, the steel tower 1 in the process of construction and a crane 11 mutually complement the strength to rocking, whereby even if the space for disposing the mast 21 inside the steel tower 1 can't be secured, the steel tower 1 can be safely constructed using the crane 11 disposed on the side of the steel tower 1.
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