The Analysis And Research On Hybrid Structure With Limit Stiffness Outriggers

Hybrid structure is the trends of tall-building and high-rise building. With the continuous increase in height of tall-buildings, frame-core tube structures with outriggers are broadly used in order to control the sideway of the whole structure under the horizontal force. Scholars from various countries have done lots of investigations and harvested fruitfully. Due to the concentration of the story stiffness, crack and displacement always occurred in the floors near the strengthened story under earthquake and the vulnerable layers are formed. This is very bad for seismic resistance. So, the suddenly changing of the stiffness of the strengthened story is the focus for the designer and investigator and the"limit stiffness"outriggers was gradually to be advanced and applied. In concept, the"limit stiffness"outriggers hopes that the whole structure stiffness satisfies the minimum requirements of standard .The structure not only meets the requirement of the sideway, but also avoids the mutations of structure stiffness .When some earthquakes seen rarely happened, the structure can present ductility yield mechanism of"strong column, weak beam"and"strong in resistance of shear force, weak in resistance of bending moment".The special work for limit stiffness outriggers was not systematic and in-depth.Based on this backgrounds, the main content of this thesis is listed as follows:(1) The author simplified the calculating model of the frame-core tube structure with outriggers. Based on the principle of minimum potential energy, considering the stiffness of the strengthened story and the influence of the prevalent floor beams, the displacement curve was got by using the seriate analysis and the formula of the sideway for the structure setting more outriggers was made by iterative algorithm.(2) Aiming at the minimum top sideway of the structure, the best position of the strengthened story was got for the structure with one, two or three strengthened layers and the conclusion consitents with the position that the standard suggests. The connection between the coefficient of the moment in the bottom of the structure and the relative location of the first strengthened layer, the stiffness characteristic parameter of outriggers, the stiffness characteristic parameter of the prevalent floor beams was studied respectively. The location of the strengthened layer under the influence of the moment in the bottom of the structure was also researched.(3) The hybrid structure with different form and stiffness strengthened layer was analyzed by finite element analysis software MIDAS. The changing of the stiffness was reflected by the changing of the sectional dimension of rods and the height of the strengthened layer. The discrepancy performance of the structure with different forms of strengthened layer was researched and the limit stiffness strengthened layer perfoming better capability than stiffness strengthened layer was proved by researching the changing rule of the periods, displacement and the internal force of the structure when the structure is under the wind and earthquake.