Simplified Analysis Of The Braced Mega-frame Structure System Of Super Tall Buildings

In recent years,the braced mega-frame structure of super tall buildings is appliedmore and more widely. With the braced mega-frame structure of super tall buildings asan example, the braced mega-frame structure of super tall buildings will be equivalentedinto tube-in-tube structure of ground,foundation and the upper structure for theintegration. And precisely calculate bending stiffness and shearing stiffness of inner andouter of the tube. According to the Hamilton principle,the differential equations andtheir corresponding boundary conditions that controlling the free vibration of theequivalent continuous modelwerederive.Finally,the equations were solved by taking ofthe ordinary differential equations solver of high efficiency and quality. the maincontents of the paper as follows:1.Modeling aspect:Generally:The mega-frame structure and its foundation aresimplified equivalently and continuously into a combination of stiffened thin-walledtubes,and columns and beams as a reinforced pole. With the braced mega-framestructure in this article, lateral stiffness ofthe first frame is increased obviously.So it’swill be equivalently and continuously into tube in tube structure.2.Equivalent stiffness calculation aspect: Because of the tube is many times for thestatic structure,equivalent bending stiffness and equivalent shearing stiffness are derivedby matrix displacement method in this paper.The inner tube is the core-tube structure.According to the equivalent method of the second chapter,equivalent bending stiffnessand equivalent shearing stiffness are derived.Because of H B5,this structure iscalculated by equivalenting to the Timoshenko Beam.3.Static analysis aspect: The braced mega-frame structure of super tall buildingswill be equivalented into thin-walled tube-in-tube structure which is supported in halfan infinite elastic foundation. Analysis of structure integrity and stability throughdescribing constitutive relation and displacement field and deriving the controlequations and boundary conditions.4. Free vibration aspect: The braced mega-frame structure of super tall buildingswill be equivalented into thin-walled tube-in-tube structure which is supported in halfan infinite elastic foundation. Natural vibration period as an important index of the structure is the focus of the analysis. Through analysis of the natural vibration periodcan be clearly obtain dynamic characteristic of structure.