Detecting And Modeling The Non-Gaussian Stochastic Phenomena In Civil Engineering Field

There are many non-Gaussian phenomena in nature,such as the wind load on the surface of open structures,the noise in wireless communication,and the fluctuation of stock prices.Since non-Gaussian distribution and Gaussian distribution have distinct statistical characteristics,it is a very important and basic task to explore and reveal the inherent statistical laws of a random phenomenon.Earthquake motion is a stochastic process with non-stationary and non-Gaussian properties.The random nature of ground motion input has a dominant effect on the structure response.Therefore,this paper is devoted to exploring the non-Gaussian random characteristics of ground motions.Based on the previous research on Earthquake motion phase,the ? stable distribution is introduced to analyze and model the Earthquake motion phase.This paper mainly studies from the following three aspects:Firstly,the concept of ? stable distribution is introduced,which is a distribution with a wider coverage and thicker tails than the normal distribution.Since the phase of the Earthquake motion calculated by the trigonometric function is discontinuous,a new method for calculating the continuous phase spectrum is proposed.we focus on the fluctuation part of the Earthquake motion phase,and use the ? stable distribution to fit the mean phase gradient of the Earthquake motion.At the same time,we analyze a large number of seismic records in the NGA seismic database and verify the non-Gaussian statistical distribution of the Earthquake motion phase.Secondly,based on the non-Gaussian characteristics of the Earthquake motion phase,an improved fractional Levy-flight process is proposed to simulate the ground motion phase,and the rationality of the method is verified.At the same time,combined with the Fourier amplitude spectrum of the real seismic records,a new Earthquake motion simulation method is proposed.Finally,due to the seismic phase has great uncertainty,we analyze the dynamics of a single degree of freedom system by generating a large number of designed response spectrum compatible Earthquake motions and obtains the yield seismic coefficients of the structure under different natural periods.By statistical analyze the yield seismic coefficients,a yield seismic coefficient demand spectrum is proposed which can be used to instruct the structural design.