Analysis And Research On The Damping Coefficient Of Isolation Structure By Using Response Spectrum Method And Time History Analysis Method

China’s Code for Seismic Design of Buildings（GB20011）（2016 Edition）puts forward the concept of horizontal damping coefficient for the design of isolation structures.The damping coefficient can be calculated by time history analysis method or response spectrum method.In order to study the difference between time history analysis method and response spectrum method in calculating damping coefficient,this paper has done the following work:（1）The development history of the isolation structure and the basic principle of the isolation structure are introduced in detail,and the content and process of the horizontal damping coefficient of the isolation structure are expounded.In view of the calculation of damping coefficient,the basic theory of time history analysis method and response spectrum method is introduced,and the research purpose and content of this paper are put forward.（2）The isolation structure is modeled by finite element software,and the selection and layout of isolation bearing for the isolation model are introduced.The period of the isolation structure is extended from 0.72 s to 1.91 s by comparing the period of the isolation structure with that of the non-isolation structure.Three groups of seismic waves,altogether 21 seismic waves,are selected to calculate the damping coefficient under the fortification intensity of the isolation structure.The damping coefficient of the first group is 0.31,the second group is 0.34,and the third group is 0.35.According to the difference of the damping coefficients of three groups of seismic waves,the relationship between the damping coefficients of three groups and the response spectra of seismic waves in the isolation period and the non-isolation period is analyzed.（3）The theory of complex mode decomposition response spectrum method（CCQC method）for isolated structures is introduced.Through the study of two equivalent linear modes of isolation bearing,it is found that the equivalent stiffness of the bearing after iteration is significantly increased compared with the 100% equivalent shear stiffness.The response spectrum method based on two equivalent linear modes of isolation bearing is used to calculate the damping coefficient,and the influence of the two equivalent modes on the damping coefficient is analyzed.The damping coefficient of three seismic waves is selected as the comparison calculation of the damping coefficient of response spectrum method,and the difference between the damping coefficient of three seismic waves and the damping coefficient of response spectrum method is compared.（4）The three seismic waves mentioned above were selected to analyze the effects of different damping ratios on the response spectrum of seismic waves,and to compare them with the standard response spectrum.A single seismic wave response spectrum was used to calculate the response spectrum method.Two methods of post-iteration stiffness and 100% equivalent stiffness were used to calculate the isolation bearing.The damping coefficient of the iterative method,the damping coefficient of 100% equal effect method and the damping coefficient of time-history analysis method were analyzed and compared.The damping coefficients of three seismic wave response spectrum methods are calculated,and the differences of each seismic wave damping coefficient structure and the reasons for the differences are analyzed.