Stability iterative method for structural reliability analysis using a chaotic conjugate map

In this paper, an iterative mathematical formula is developed to control instability solutions of first-order reliability method (FORM) using chaotic conjugate map. A nonlinear discrete map is proposed using a conjugate line search and a chaotic step size to search the most probability point. The chaotic step size is adjusted based on a finite-step size using Armijo line search and logistic map. A chaotic control factor is established using stability condition based on the results of the new and previous iterations, namely conjugate chaos control (CCC) method. The unstable solutions (i.e. periodic and chaos) of FORM without control are investigated using several nonlinear mathematical and structural/mechanical problems. The nonlinear conjugate map of FORM is accurately yielded to stable results. The CCC can improve the convergence speed of the FORM for concave and convex nonlinear problems. The CCC is more robust than the FORM algorithm without control and is more efficient than the other modified version algorithms of FORM.