PURPOSE: To properly perform the tension introduction to a chord beam, thereby preferably executing lift-up work, sufficiently ensuring the structural stability of a structure, and also improving the safety of construction.

CONSTITUTION: A flat square roof frame 2 is ground-assembled, main pillars 3 are also constructed in its corner part positions, and the roof frame 2 is finally lifted up and supported by the main pillars 3. At this ground assembling work, chord girders 6 are radially assembled from the form center of the roof frame 2 toward the respective corner parts where the main pillars 3 are situated. Chord beams 9 are ground-assembled in triangular roof parts 8 partitioned by the chord girders 6, and the roof finishing work is conducted on the ground to the chord girders 6. A tension is thereafter introduced to chord members 5, 8 of the chord girder 6 and others. Thus, the roof frame 2 is perfectly constructed by the ground assembling work, and in the final stage of the completion, the tension is introduced to the chord members 5, 8.