The Shifted Generalized Lognormal Distribution (SGLD) And Its Applications In Structural Reliability Assessment

Due to the uncertainties of environmental effects? material properties?and geometrical parameters,the load effect(structural response)has significant uncertainties.According to statistics,70% of the structural collapse in China is caused by the estimation error of the load effect.Uncertainties of load effects exist in all structures,and are one of the key issues in structural safety design and evaluation.The difficulty of structural system reliability assessment lies in how to identify the failure modes and the construction of joint distribution of maximum load effects.The method of structural failure mode identification has been studied for a long time.At present,the methods developed include Engineering criterion method,Minimum load increment method,?-bound method,Branch-approximate method and Cut-off enumeration method.The validity of these methods has been verified in their respective applicability.The problem of joint distribution of maximum load effect has been studied for many years,the most commonly used methods are probabilistic network evaluation(PNET),reliability narrow bound,Monte Carlo stochastic simulation and so on.For the high-reliability structure and the complex structure system considering the correlation,these methods can not give the analytical solution,and the computational efficiency and precision can not meet the engineering requirements.In view of this,this paper considers the reliability estimation problem of high reliability structural system,and deeply studies the application of SGLD model in the construction of tail model of edge distribution of structural load effect and reliability analysis of high reliability structure.The main contents of this paper are as follows:1.Tail model of edge distribution of structural load effect based on SGLD model and tail model of joint distribution of structural load effect based on Copula funcation and parameter estimation of the models.2.Study on the method of estimation of the micro-failure probability of structures under non-Gaussian loadings.3.Study on the method of estimation of the micro-failure probability of structures under non-Gaussian loadings based on ANSYS.4.Research on algorithm of multivariable Normal distribution with high correlation.5.Engineering application analysis of theoretical research achievements.Based on the above research,a parameterization method for the tail estimation of high-reliability structure based on Shifted Generalized Lognormal Distribution(SGLD)and Copula model is established,as well as analysis method of high reliability structural based on ANSYS and calculation method of multivariate normal distribution with high correlation.The study of the micro failure probability of the structure under the nonGaussian load shows that the SGLD model and Copula function can give the analytical expression of the joint distribution of the load effect of the high reliability structure and can effectively calculate the high correlation structure of the micro-failure probability.The research of this paper not only establishes effective estimation method of micro-failure probability of high reliability structure,but also improves its engineering value and application range by ANSYS software and algorithm of multivariate normal distribution with high correlation,and has important theory and application value.