Study On Reliability Analysis Of Long Span Suspension Bridge Based On SVM-PSO Algorithm

Based on the basic theory of structural reliability,this paper presents a reliability calculation method based on SVM-PSO algorithm for solving the problem of the existing reliability calculation method in solving the complex structure reliability index.The reliability analysis of a long span suspension bridge is carried out by this method based on deflection control and stress control,and the sensitivity of random variables is analyzed,finally we draw some conclusions for the future design and construction of similar bridges to provide certain reference value.The main contents of this paper are as follows:(1)The existing reliability calculation methods are analyzed and summarized,such as,the FORM method and SORM method can't solve the reliability index of implicit function,and to the complex nonlinear structure it is not easy to converge.Monte Carlo method to solve the reliability index requires a lot of sampling,low efficiency.Two polynomial response surface method is not accurate enough;neural network response surface method is easy to fall into local optimum.(2)In order to overcome the shortcomings of the existing reliability calculation methods,this paper presents a reliability calculation method based on SVM-PSO algorithm,and proves the feasibility of this method by some examples.This method combines the advantages of the SVM response surface method of small sample learning ability,high fitting precision and PSO algorithm has strong searching ability and fast convergence,can solve the implicit function is very good and the reliability index is not convergence.(3)The finite element model of the bridge is established,The reliability analysis of a long span suspension bridge is carried out by this method based on deflection control and stress control,using the PNET method to analyze the reliability of long-span suspension bridge based on stress control.The results show that the structure has a high reliability index under two failure modes.(4)In order to investigate the influence of the random variables on the reliability of the suspension bridge,the sensitivity analysis of the random variable of the long-span suspension bridge under two failure modes is carried out.And in order to observe the change trend of the reliability index with random variables,the single parameter variation analysis of the random variables with high sensitivity is analyzed.