Design and construction of frame structure with span of 25.2m

In order to enlarge the room of the first floor in Guojian high-rise side building, beam and slab of the second floor is hanged from the roof girder. This paper introduces the special frame design, comparison of internal force of roof girder in three different input situations, and the scheme selection. Construction methods of High-level bracing and the girder on the roof with area of 600mm×3000mm are introduced, and the bracing demolition scheme which meet the requirement of load once.