Dimension Reduction Model Of Ground Motion With Random Parameters And The Seismic Reliability Analysis Of Frame Structure

Earthquake motion has significant random dynamic characteristics,time-frequency nonstationary characteristics,etc.In seismic analysis,in order to describe the randomness of ground motions and study its influence on structural response,the process of ground motions is generally abstracted as a random process,and the power spectrum model is usually used to describe the random characteristics of ground motions.Therefore,Therefore,giving reasonable values for the parameters in the power spectrum model is of great significance to the analysis of the random seismic response of structures.In the current research stage,the random ground motion model is combined with the actual design.The parameter values of the random ground motion model given in accordance with the seismic code are all deterministic values,which are only a rough consideration and cannot reflect the complexity and uncertainty of site conditions and the discreteness of ground motion characteristics.In this paper,considering the influence of the complexity and uncertainty of site conditions on ground motions,two kinds of ground motion dimension reduction simulation model with random parameters are proposed.Combined with numerical simulation examples,the effectiveness of the proposed dimensionality reduction model is verified.At the same time,combined with the probability density evolution method to evaluate the seismic reliability of the frame structure to illustrate the engineering application value of the method in this paper.The main work of this paper is as follows:Firstly,introduces the dimension reduction simulation method of the spectral representation of non-stationary random processes,and the connection between traditional simulation methods and spectral representation based on orthogonal random variables is clarified.The expressions of the non-stationary random process based on the random phase method（DSA）dimensionality reduction simulation method and the random amplitude method（NSA）dimensionality reduction simulation method are given.Secondly,in order to consider the randomness of ground motion amplitude,frequency spectrum,and duration of the ground motion,the site parameters and the time-frequency modulation parameters in the evolutionary power spectrum model of the non-stationary ground motion process as random parameters.Two kinds of ground motion dimension reduction simulation model with random parameters is constructed.The point selection method based on partial stratified sampling are used to select representative point sets of basic random variables to generate a representative time history set of non-stationary ground motions,and the numerical simulation results are analyzed in detail.At the same time,the consistency of the Fourier amplitude spectrum and acceleration response spectrum of the measured strong motion records with the representative time history set of the non-stationary ground motion random field generated by the dimensionality reduction model is compared to verify the engineering applicability of the dimension reduction simulation model.Finally,the representative time-history set is generated through the non-stationary ground motion random process dimension reduction simulation model with random parameters.Combining the probability density evolution method to analyze the dynamic response of the frame structure model,and obtain the evolution process of the structural response in its probability space.Taking the elastoplastic interlayer displacement angle as the seismic reliability index of the structure,a refined analysis of the seismic reliability of the nonlinear frame structure under two different working conditions is carried out.The effectiveness of this method is verified from the perspective of engineering practice.