Abstract
In this study, the tunneling algorithm is applied to the first order reliability method (FORM) to find a global design point. In the FORM, the structural reliability is evaluated as the minimum distance from the origin to the limit state surface in the standard normal distribution space. Therefore, the FORM is formulated as a nonlinear optimization problem. However, it is difficult to find the design point, when the limit state surface has several local minimum points such as a case of the laminated composite plate subject to the first ply failure. In general, the original tunneling method is not worked well for the constraint problem. In this study, a new tunneling function suitable for the FORM is proposed to find the other design point which has a lower objective function value and satisfies the equality constraint. In the tunneling function, the limit state function is treated as a kind of a penalty term with a pole. Through the reliability analysis of a laminated composite plate subject to in-plane loads, the efficiency of the proposed tunneling function is demonstrated. Also, the selection of the penalty parameter is suggested.
