To provide the assembling method of a column-rib field assembling, in which the efficiency of operation is improved and certainty is attained, by facilitating operation by externally inserting hoops to a column rib under the state, in which the column rib is self-sustained, while the hoops previously field-assembled under the state, in which the hoops are superposed, are inserted externally to the column rib collectively.

Column ribs 4 and hoops 6 are assembled in the assembling method of column-rib field assembling 10. The lower sections of the column ribs 4 are inserted into a plurality of pipes 3 being fixed and arranged onto a base in response to specified column-rib intervals and having an inside diameter corresponding to the diameter of the column ribs 4 respectively, the hoops 6 are inserted externally to these column ribs 4 under the state, in which each column rib 4 is erected by these pipes 3, and column-rib field assembling 10 is assembled. A fixed number of the hoops 6 are superposed and assembled previously in specified order and formed previously as hoop field assembling 5, and the hoops 5 are inserted externally to the column ribs 4 collectively by externally inserting the hoop field assembling 5 to a plurality of the column ribs 4 erected at regular intervals.