Study On The Analysis Method Of Inter-story Isolated Structure Considering The Non-proportional Damping

At present,the seismic isolated structure design in code for design of building isolated is based on classical damping,which is only suitable for ordinary structures with small damping,and not applicable for the large damping isolated structures.The problems of Rayleigh damping for base isolated structures are explained by investigating base isolated structures.Working with inter-story isolated structures.Based on the complex mode theory and response spectrum method,the influence of different construct methods of non-proportional damping matrix on the performance of the inter-story isolated structure is studied.A new method based on equivalent linearization,complex mode decomposition principle and CCQC combination is proposed,Based on the integrated design results,the static pushover method(Pushover)for inter-story isolated structure is researched,and an improved multi-mode Pushover Method(IMPA)for inter-story isolated structure is proposed.The rationality of this method is verified by the dynamic elastic-plastic analysis.The research contents of this paper summarized as follows:(1)Starting with base isolated structures,based on the inter-story isolated structure,three methods are respectively used to convert the damping coefficient by the partition Rayleigh damping,mode superposition damping coefficient and damping ratio conversion coefficient by MATLAB numerical analysis platform.According to the characteristics of the inter-story isolated structure,four different global non proportional damping matrix are constructed.The applicable damping matrix is judged by parameter analysis.In this paper,based on two different natural wave response spectra,the influence of damping matrix formation on structural response is analyzed by using,CCQC and CQC methods.The change of equivalent period and equivalent damping ratio of isolation layer is discussed and analyzed.The application range of CQC and CCQC methods is discussed by changing equivalent period and equivalent damping ratio of the isolation layer.The results show that the design response spectrum CQC and CCQC are used to study.The influence of different equivalent periods and damping ratios on the error of story displacement and story shear fore by CQC and CCQC methods.(2)The mechanical models of several commonly used bearings are introduced.The applicability of complex mode CCQC response spectrum method to inter-story isolated structure with different types of bearings is briefly discussed.The iterative process of equivalent stiffness and damping coefficient of lead rubber isolation bearings is emphatically described.The characteristics and design process of the traditional isolated structure design method and integrated isolation design method are presented.Finally,taking the large chassis frame structure as the research object,the interlayer isolation design is carried out by using the divisional design method and the integrated design method respectively.In order to further study the performance of the interlayer isolation,the structure is analyzed from the perspective of energy.The seismic responses and costs of the isolated structure designed based on the two different methods are compared.In addition,the direct analysis of bearing nonlinearity is considered.In this paper,the influence of non-proportional damping on the design of isolated structures is studied by the design method and the integrated design method.(3)Based on the equivalent linearization results of inter-story isolated structure and the requirements of the standard for seismic isolation of building structures.The damping ratio of the structure is obtained by the complex modal analysis method.The elastic-plastic response spectrum of isolation is introduced as the demand spectrum by improving the equivalent damping ratio in the capacity spectrum method.According to the performance of inter-story isolated structure,the improved capacity spectrum method is combined with the modal Pushover Method.Base on this,a new method is proposed,which can not only consider the nonlinearity of isolation story,simplify the traditional modal pushover static elastic-plastic analysis method(IMPA)for solvinge the target displacement.Taking the inter-story isolated frame structure designed by the integrated design method as an example,the floor response under very rare earthquake is studied,and the pushover results under different horizontal load modes are analyzed.Rationality and relative superiority of the method are evaluated and verified based on the results obtained by dynamic elastic-plastic analyses.