A Study On Complex Modal Response Spectrum Method For Seismically Isolated Structures

Isolation technology is a kind of anti-seismic technology with good damping effect,and it has been recognized and applied in many countries.With the promotion of isolation technology,it is of great significance to study efficient and reliable methods for the structural dynamic response analysis.At present,there are three main types of seismic response analysis methods for isolated structures: time history analysis method,random vibration analysis method and spectrum method,and the more commonly used methods in these methods are unique,and there are some shortcomings.The complex modal method can accurately deal with the non-classical damping problems existing in structural response analysis,and the isolated structure is also a structure with nonclassical damping characteristics.In this study,the complex modal response spectrum method for dynamic response analysis of isolated structures is studied,the main contents of which are as follows:(1)The research and development of isolation technology at home and abroad are summarized in detail;and the structure,characteristics and nonlinear resilience model of isolation rubber bearing are comprehensively discussed;The development process and research of the complex modal analysis and the dynamic response analysis method of isolation structure are introduced in a more comprehensive way.The dynamic response analysis method includes time history analysis method,random vibration analysis method and response spectrum method.(2)Study the complex modal analysis method,and on the basis of the conventional CCQC(Complex Complete Quadratic Combination)response spectrum method,combined with the equivalent linearization of the isolation bearing,a modified CCQC response spectrum method for the dynamic response analysis of the isolation structure is proposed—equivalent iterative CCQC response spectrum method.(3)The validity and accuracy of the method are studied and verified.On the MATLAB numerical analysis software platform,the equivalent iterative CCQC response spectrum method is used for the dynamic response analysis of simple numerical examples;and 100 artificial seismic waves are simulated according to the acceleration design response spectrum,which is used for nonlinear time-history analysis of simple example model.The average of the response maximum calculated by nonlinear time-history method is taken as the reference value,and the results of this method and the results of conventional CCQC response spectrum method are compared and analyzed.(4)The proposed method is applied to the response analysis of three-dimensional foundation isolation structure.Using the general finite element software SAP2000 to verify the correctness of the three-dimensional foundation isolation elastic model established by the selfcompiled MATLAB program,then the equivalent iterative CCQC response spectrum method and nonlinear time-history analysis method are used to analyze the three-dimensional structure and compare the dynamic response results,which lays a foundation for the engineering application of the method proposed in this paper.