The Dynamic Characteristics Of High-rise Building System To Vertical Seismic Action

Vertical seismic action has become a more and more important subject to engineers in recent decades. The earthquake macro-phenomena have demonstrated that the influence of the vertical seismic motion is obvious in high intensity area. There are huge masses on the transfer beams of the tall building structures with transfer layers and the mega-beams of the mega-structures, so they will be sensible to the vertical earthquake forces. Therefore, the dynamic response analysis of this kind of structures is very important.In many references tall buildings are modeled as the shear building, that is "story model", while analyzing the response of the buildings due to the vertical seismic excitation. In a few references tall buildings are modeled as "series-parallel-connection system model". The "story model" has more suitability in the analysis of the horizontal seismic action on tall buildings. However, to tall buildings under vertical seismic action, the postulate that each column has the same displacement in the same floor is impossible confirmation. Furthermore, in the story model, the computational results only reflect the change of the axial forces of the columns due to vertical seismic action, but it can't reflect the change of the internal forces due to vertical seismic action. The joint rotation is often neglected, while using series-parallel-connection system model analysis the response of the buildings due to the vertical seismic excitation. In order to access actual engineering, it is necessary to establish a new model to analyze vertical seismic action on the tall buildings.This paper presents the series-parallel-connection model considering joint rotation. To the dynamic matrix of tall buildings, through dynamic force condensing, the coupling relationship of vertical displacement and rotation is eliminated. Therefore, the degree of dynamic matrix and the quantity of earthquake-resistant calculation are lowered. The results of the computational example show that the proposed method is much more rigorous. At the same time we can educe some dynamic response characteristics of tall buildings subject to vertical earthquake action; it is valuable to engineering design.