FINITE ELEMENT-BASED STRUCTURAL RELIABILITY ANALYSIS OF CABLE-STAYED BRIDGES

摘要

With the inherent uncertainties in material properties, loading, boundary condition and geometry, it is necessary to assess the safety of cable-stayed bridges in stochastic domain. Though great progress has been made to assess the reliability and safety of simple civil structures, there are more efforts needed for the reliability analysis for the highly indeterminate structures such as long-span bridges, tall buildings. 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 (FDM). 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 β of the cable-stayed structure. The proposed procedure is applied to the reliability assessment of cable-stayed bridges. The main girder and pylon are modeled by using beam column elements, while the stay cables are modeled as truss elements with Ernst modules. 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 the cable-stayed bridge is estimated at serviceability limit states.