Evaluating the Failure Probability of Rectangular Plates with Different Boundary Conditions Using a Dynamical Finite-Step Length Method

The performance of plates can be changed due to their uncertainties in applied loads, material properties, geometry and boundary conditions. In this paper, the failure probabilities of rectangular steel plates are evaluated using the displacement performance function using the first-order reliability method (FORM) – based on a novel finite-step length. The displacement limit state function of the isotropic plates for different boundary conditions is used for their reliability analysis based on the random variables such as material, plate dimensions and applied external load which have been simulated by use of Normal and Lognormal distribution functions. The finite-step length of FORM is developed based on Armijo line search that is simply computed and is improved the robustness and efficiency of FORM. The results demonstrate that by decreasing plate dimensions, the failure probabilities are decreased. The failure probabilities of plates with free boundary conditions are obtained to be more than the failure probabilities of plates with clamped boundary conditions. The minimum thicknesses of rectangular plates with simply supported conditions are found to be about (around plate)/300 to achieve a reliable performance.