Research On The Dynamic Performance Of The Tall Building Mega Sub Structure

The Mega Sub Structure is a kind of new high-rise building structure,proposed by the American scholar MariaQ.F and Akira Mita in 1995.It combines the structural control of ideas and general mega-frame structure which is made up of two classes frame structure.It ingeniously applies the principle of tuned mass damper and multiple tuned mass damper for the structure.While meeting the functional requirements of buildings, it relies on its own functional unit structure (sub structure) to achieve response control, forming a self-damping structural system.Currently,the Mega Sub Structure did not have engineering examples at home and abroad.It is necessary to research on the reasonable form, self-damping effects, characteristics and calculating method of dynamic response and the factors in-depth.In this paper, based on previous studies, in order to make the results more accurately reflect the mechanical properties of the actual structure,it refers to TC Building in Kobe, Japan, the Japanese NEC office building structure.A finite element model is established. To solve the collisions problem between mega structure and sub structure in the Mega Sub Structure, and the acceleration response too large and so on, a damper is installed in the top of the sub structure.First, modal analysis, discuss dynamic characteristics of the Mega Sub Structure dynamic characteristics. Second, carry on time history analysis to the Mega Sub Structure in the seismic excitation,and compare with the general mega-frame structure.Using single point response spectrum (SPRS) in the finite element analysis software dynamic analysis method, study on the controlling parameters such as:additional damper damping coefficient, the additional damper position set on the structure, the ratio of the stiffness by sub structure to mega structure, the ratio of primary frequency by the sub structure to the mega structure and so on,to get the effects on control performance in this structure.The results show that the controlling effect is obvious for the acceleration and displacement of mega structure and the sub structur in the Mega Sub Structure.By choosing appropriate sub structural parameters,it can be better control the displacement and acceleration response of the mega structure and the sub structure in the earthquake.Choosing reasonable damping coefficient value of additional damper will not change the characteristics of self-tuned of the Mega Sub Structure.and the additional damping can make the dynamic response significantly reduced.When the additional dampers are set on the top of the sub structure, it is the best for the dynamic response control on the Mega Sub Structure.The conclusion from this paper provide a reference for the research and engineering practice on the Mega Sub Structure.