Calculation Of Sub-linear Equations In The Reliability Approach

The reliability analysis of nonlinear limit state equations is important in engineering practice.The method of AFOSM is effective in reliability analysis,but it is not precise enough.It is the focus that how to improve the accuracy of nonlinear limit state equations reliability analysis . The approaching method transforms the nonlinear limit state equation into an associated-linear system,it is effective in improving the reliability analysis accuracy.Based on the analysis and comparison of existing approaching methods,the paper points out that the key to the method is how to choose the linear limit state equations,and it has significant impact to the accuracy and efficiency.In this paper , an effective method is given to calculate the sub-linear limit state equations.Based on the obtained nonlinear equation,the next expansion point and linear limit equation are acquired with optimally iterative calculation . The correlation coefficient between two adjacent linear equations is used to judge the gained sub-linear equation is proper or not.Finally,the linear approximation model with higher precision is established.The analysis and examples show that the method presented in this paper is feasible and effective.It has considerable value in theory and practice,and also provides a reference for the further research and amelioration.