Concrete performance time-varying effect of CFST arch bridges

Concrete-filled arch ribs of concrete-filled steel tubular (CFST) arch bridges experience temperature effects and shrinkage/creep effects, as well as effects based on their interaction, that reduce the calculated stiffness of the arch ribs of the CFST arch bridges, resulting in a reduced bearing capacity. To address this problem, this paper proposes a Gaussian process response surface method based on the concept of dichotomy. When the training sample parameter interval is uncertain, it achieves the fastest retrieval of training samples that meet the requirements, it makes up for the shortcomings of the traditional small sample Gaussian process method. It can accurately predict the equivalent stiffness of the concrete-filled arch ribs of the CFST arch bridge, considering the effects of temperature and time, and grasp the time-varying degradation law of the mechanical performance of the CFST arch bridge arch rib. To verify the correctness and reliability of the proposed method, a refined analysis model of a CFST arch bridge is established using the general finite element software ANSYS, and the optimal creep equation and temperature effect function are selected. Using the improved Gaussian process model, the equivalent calculated stiffness of the arch rib filled with concrete after ten years under the combined action of shrinkage, creep and temperature effects of the concrete-filled steel tube arch bridge is predicted, and the deflection value and stability coefficient are proposed as the evaluation index of the prediction accuracy. The research results show that the proposed method provides a more simplified and high-precision method for the performance degradation analysis of concrete filled steel tube arch bridge arch ribs under the coupling action of complex factors such as shrinkage, creep, and temperature effects.