Study On The Strenhened Story And Liminted Stiffness Of Theframe-Core With Horizontal Steel Trusses

With the rapid development of national economy, high-rise buildings have gradually become the current trend of building development. Among which the frame-core tube structure with a strengthened story is increasingly used in high-rise buildings due to its sparse columns、large space and ability to control the lateral displacement of structure effectively, yet such structures remain complex, particularly its complicated stress in strengthened story, for which in-depth research and analysis are requiredIn this paper, take a52-story frame-core tube structure with a strengthened story—whose strengthened story is level cantilever steel truss structures—for instance, the study include strengthened layer’s location、number and the impact of level cantilever’s stiffness to the whole structure’s stiffness. Meanwhile,SAP2000is used to build a three-dimensional finite element model, under wind loads and horizontal seismic action as well as series of elastic analysis, conclusions come as follows:(1) In the frame-core tube structure, the more reasonable position of setting level cantilever steel truss structures with a strengthened story is:one strengthened story should be set at0.5times the height of the building,and two strengthened story properly set1/3、2/3of the whole building’s height, while three or more strengthened story should be set along the structure vertically and uniformedly, but not suitable in the top layer.(2) In the frame-core tube structure, the number of features to set level cantilever steel truss structures with a strengthened story is:the most effective way to reduce top drift of a struture is to set one strengthening layer; later with the increasing number of layers, strengthening layer affect the struture ’s top drift gradually decreased,and to each a building, it’s proper to set a layer every15～20stories,but should no more than4strengthening layer.(3) The study of level cantilever structures’s stiffness within the frame-core tube structure with a strengthened layer shows that:in high-rise structures, the ratio of outer horizontal outrigger arm member to the inner cylinder member’s bending stiffness should not exceed0.4when setting one level steel truss cantilever strengthening layer, and the ratio of outer member to the inner member’s shearing rigidity required no more than2.3, besides, the ratio of outer frame column to the inner cylinder one should be controlled within the range of2～4.