Reliability Analysis of Core Concrete Creep Effect on Concrete-filled Steel Tubular Arch Bridge

In order to investigate the creep effect of the core concrete on construction period and service performance of concrete-filled steel tubular arch bridge, by using adjusting valid modulus depending on age method, the creep coefficients derived by Code for Design of Highway Reinforce Concrete and Prestressed Concrete Bridges and Culverts(JTG D62-2012), creep experiment of the concrete-filled steel tube under axial compression and arch rib were applied to establish the ANSYS model, putting creep processes of concrete into consideration to analyze the creep effect of the concrete on the down deflection of main arch rib of Maocaojie bridge during the construction. The reliability analysis was conducted by Latin hypercube sampling method based on the functions of deflection and steel stress of mid-span arch rib to predict the failure probability of Maocaojie bridge during the service period, taken elasticity modulus of concrete and steel, tube wall thickness of upper and lower chords tubes, ventral tubes, uncertain coefficients of creep model, uncertain coefficients calculated by the elastic modulus of the core concrete and uncertain coefficients of FE model of Maocaojie bridge as parameters. The results show that during the construction, the arch deflection values, calculated by the creep coefficient of the creep test of arch rib, are coincident with the measured values, which verifies the applicability and accuracy of the developed model. During the service period, when the service limits increase to 100 years, the failure probability of bridge gradually increases and differences among results calculated by different creep coefficients of concrete are obviously large, taken rib deflection and stress as limits. According to Equation (1), (2) and (6), the failure probability of the bridge is 0.311, 0.013 8 and 0 based on the rib deflection limits, and is 0.499, 0.225 and 0.165 2 based on the stress limits. So the key problem is to choose the right creep model for creep reliability analysis of concrete-filled steel tubular bridge. © 2017, Editorial Department of China Journal of Highway and Transport. All right reserved.