Study On Seismic Analysis Of Structures Based On Non-stationary Stochastic Process Theory

Structural seismic analysis is an extremely complex and challenging subject,and has always been one of the hotspots and difficulties in structural engineering,geotechnical engineering and mechanics.In most cases,seismic design is also a control condition of the building structural design.At the same time,because the structural seismic analysis is very comprehensive,involving the earthquake,materials,mechanics,engineering and other disciplines,we need to combine the knowledge of the related disciplines.Once the structural seismic method is used improperly,the intended seismic fortification target will not be achieved,even in the event of a strong earthquake,the building will collapse and damage.Because the seismic wave has very strong nonstationarity,the traditional Fourier transform can only obtain the information of its frequency domain and can not obtain the time-varying spectrum information.At the same time,because the seismic wave has very significant spatial non-uniformity,the nonstationarity and spatial non-uniformity together have a very huge impact on the response of the structure under earthquake action.These characteristics of seismic waves bring more challenges to structural seismic research.Structural dynamics has been widely used in structural seismic research.At present,the time and frequency domain analysis and calculation methods are mainly used.Due to the characteristics of time-varying frequency spectrum of seismic wave,the traditional calculation method can not meet the engineering application requirements,and there is an urgent need for the establishment of time-frequency domain analysis and calculation method.In order to solve the problem of the traditional time domain or frequency domain method,the wavelet transform is applied to the structural seismic analysis.But the use of wavelet transform to solve the problem also faces many difficulties,such as the relationship between the scale parameters and the frequency involved in the wavelet transform.In this paper,the nonstationary stochastic theory is introduced into the traditional structural seismic theory.Based on the time-frequency analysis theory of wavelet transform,the time-varying power spectrum model and structural dynamic analysis method of seismic wave are established.The following results are obtained:1.Based on the nonstationarity characteristics of seismic wave,the time-varying power spectrum estimation of recorded seismic waves is calculated by time-frequency analysis method,such as wavelet transform.Combining with the existing power spectrum model,according to the conditions of the site classification,the time-varying seismic wave power spectrum model is established,and the relevant model parameters is given.Based on the data collected from the existing seismic arrays,the spatial variation characteristics of ground motion are studied,and the spatial non-uniform model of ground motion is established.2.The wavelet transform method is introduced into the traditional theory of structural dynamic calculation,and the time-frequency model and the dynamic analysis method of the structure are established based on the wavelet transform theory.3.Through the theoretical analysis and the response spectrum of the real strong earthquake,and through statistical analysis,a clear physical meaning,a more simple form and more reasonable safety factor seismic response spectrum unified calculation formula is established.4.Using the actual strong earthquake seismic wave,by adjusting its spectral information,the artificial seismic acceleration time history is compatible with the design response spectrum,and its nonstationarity is similar to the actual seismic wave.5.Based on a case study of a special type cable-stayed bridge,the realization process of seismic analysis method based on nonstationary stochastic theory is discussed in detail.Based on the practical engineering example,the feasibility of seismic analysis based on non-stationary stochastic theory is analyzed,which reflects the engineering significance of seismic analysis method based on nonstationary stochastic theory.The results of this study are based on the high nonstationarity of seismic wave and the response of the structure under the earthquake.The time-frequency analysis method such as wavelet transform should be used for seismic wave input,structural model establishment and so on.,which can provide reference for future research on seismic structure and provide the necessary foundation for structural seismic optimization design.