FINITE ELEMENT-BASED STRUCTURAL RELIABILITY AND SENSITIVITY ANALYSIS OF A SINGLE-PYLON CABLE-STAYED BRIDGE

The reliability analysis of the highly indeterminate structures such as long-span bridges is a challenge for researchers because of its complexity. The common reliability analysis methods such as Response Surface Method (RSM) and Mont Carlo Sampling method are not suitable for large structures due to their inherent inefficiency in computation. Based on the stochastic finite element method, an approach for the reliability analysis of long-span cable-stayed bridges is presented. The gradients of limit-state functions involving finite element response quantities are computed with Direct Differentiation Method (DDM) which is much more efficient and accurate compared with the finite difference approach. A procedure which combined with the first order reliability method (FORM), second order reliability method (SORM) and important sampling method (ISM) is implemented to evaluate the reliability index beta of the cable-stayed structure. The proposed procedure is applied to the reliability assessment of Huangpu cable-stayed bridge. The element configurations are in CR formulation, which accounts for the geometrical non-linearity due to the effects of the cable sag, interaction of axial forces and bending moment and large deflection. The reliability index of Huangpu cable-stayed bridge is estimated at ultimate limit states. After the reliability analysis, the sensitivities of the means and the standard deviations of the random variables are calculated, which dominate the evaluation of the reliability index beta.