Reliability Analysis Of Simply-supported Beam Bridge-track System With Unequal Pier Height Under Stochastic Earthquake Based On RBF-PDEM

The difference of pier dynamic characteristics has a significant impact on the nonlinear seismic response of simply supported beam bridge-track system with unequal pier height.The reliability analysis of structure under disastrous dynamic action is very important to evaluate structural performance and ensure structural safety,while the deterministic seismic damage analysis method is not enough to accurately reflect the overall behavior of stochastic dynamic system.Therefore,in order to predict the deformation reliability of key components(pier tops,bearings and fasteners)under stochastic earthquakes,this thesis firstly carried out research on the selection of highly representative stochastic seismic samples and the improvement of solving accuracy of probability density evolution equation.Then,the nonlinear finite element model of simply supported beam bridge-track system with unequal pier height is established,and the CRTS-Ⅰ type unit-slab ballastless track is adopted.Finally,based on radial basis function(RBF)and probability density evolution method(PDEM),the deformation reliability of key components is analyzed.The specific research contents and results are as follows:(1)A stochastic point set selection method based on adaptive sampling scheme is developed.Reasonable stochastic earthquake input is very important for the response analysis of simply supported beam bridge track system with unequal pier height.Based on the adaptive sampling scheme,a stochastic point set selection method with controllable quantity and accuracy is developed in this thesis.Compared with the traditional point set selection method,the feasibility of the adaptive sampling scheme is verified.Based on the adaptive sampling scheme,the seismic samples considering the randomness of Clough-Penzien(C-P)spectrum parameters are simulated,which provides stochastic seismic samples with richer probability information for the subsequent reliability analysis of simply supported beam bridge track system with unequal pier height under stochastic earthquake.(2)The improved initial condition and the selection formula of differential time step are proposed.When the reliability analysis of simply supported beam bridge track system with unequal pier height is carried out based on PDEM,the difference accuracy of probability density evolution equation has a significant impact on the accuracy of reliability results.By deriving the differential solution process of probability density evolution equation,this thesis finds out the factors affecting the accuracy of differential solution,and puts forward a smoother normal distribution initial condition and a more reasonable selection method of differential time step,and gives the differential time step for PDEM analysis of bridge-track system,which provides a preliminary basis for the solution of probability density evolution equation of equivalent extreme-value in subsequent reliability analysis.(3)The reliability analysis of key components of simply supported beam bridge track system with unequal pier height under stochastic earthquake is carried out.Based on OPENSEES software platform,the finite element model considering the nonlinearity of piers,bearings and fasteners is established,Among them,the CRTS-Ⅰtype unit-slab ballastless track is adopted,and then the response of key components corresponding to stochastic seismic samples is calculated based on the nonlinear finite element model.Then,by expanding the application scope of adaptive sampling scheme,the prediction model between seismic sample variables and equivalent extreme-value is established based on RBF.The effectiveness of RBF-PDEM method is verified by comparing with the deterministic analysis results.Finally,the effects of error termination conditions,peak acceleration of ground motion,pier height and variation coefficient of C-P spectrum on reliability of different components are analyzed,and the overall reliability results of simply supported beam bridge with unequal pier height are given.Figures 117,Tables 17,References 135...