Prediction Formula for Temperature Gradient of Concrete-Filled Steel Tubular Member with an Arbitrary Inclination

Concrete-filled steel tubes (CFSTs) have been used extensively as main members with different inclinations in bridge structures; however, investigations on the influence of member inclination on temperature gradient are inadequate. To fill this gap, long-term measurements were made of the structural temperature of three CFST members with inclinations of 0°, 45°, and 90°, along with simultaneous meteorological parameters, including solar radiation, air temperature, and wind speed. It was found that distinctions do indeed exist in the sun-side temperature differences of CFST members with different inclinations. Subsequently, by stepwise regression of the accumulated temperature and meteorological data, an empirical formula was established to predict the daily maximum temperature difference of CFST members of arbitrary inclination. Finally, finite-element modeling was performed on the temperature field of a CFST arch bridge and verified the proposed formula with a high degree of confidence. Therefore, the proposed prediction formula and the corresponding method can provide relatively valuable references for the improvement of the thermal design of CFST bridges in current specifications.