Analysis of three-dimensional temperature distribution characteristics and temperature-induced frequency variation for continuous rigid frame bridges

Abstract

Long-span bridges are continuously exposed to natural environmental conditions, influenced by factors such as solar radiation, wind field disturbances at the bridge site, and seasonal variations. These factors lead to the gradual formation of non-uniform temperature distributions within the structure, which may result in disadvantageous changes in the dynamic characteristics of the bridge. However, existing studies lack detailed three-dimensional (3D) temperature field simulations and analyses of temperature-induced dynamic characteristic variations for long-span continuous rigid-frame bridges. This study proposes a refined 3D temperature field simulation method for long-span continuous rigid-frame bridges. Using this approach, the 3D temperature distribution characteristics of a four-span continuous rigid-frame bridge were investigated, and the time-varying uniform temperature of the structure was obtained. A finite element model of dynamic behavior of long-span continuous rigid-frame bridge was developed to explore the variation patterns of its dynamic characteristics under thermal effects. The results indicate that the proposed model can accurately reflect the 3D temperature distribution characteristics of the structure, with longitudinal temperature variations found to be insignificant. The calculated uniform temperature of the structure using the proposed method agrees well with the results of recommended formula. Furthermore, the fourth-order frequency exhibits the most significant variation under temperature effects. The variations in the first three natural frequencies are consistent with the amplitude of uniform temperature changes, while the temperature-induced frequency variations in high temperature environment of the fourth and fifth modes show limited sensitivity to changes in the uniform temperature of the structure.