Bridges are inevitably affected by daily, seasonal and annual air temperature and solar radiation. The thermal effects on bridges, especially for long-span cable-stayed bridges with composite girders, are significant and complicated. The evaluation of temperature distribution has been a primary concern to bridge engineers and researchers. This article presents a more than one-year temperature database of a long-span cable-stayed bridge with a small cantilever length-to-web depth ratio in the composite girder. Uniform temperature, linear temperature difference, thermal curvature, and self-equilibrated thermal stress are considered to imply the characteristics of the temperature distribution in such composite girders. Two profiles (profile 1 and profile 2) for positive vertical temperature gradient and one profile (profile 3) for negative vertical temperature gradient are proposed. The extreme temperature differences with a 100-year return period are determined for each profile with extreme value analysis. Among the three profiles, profile 2 is unique for composite girders with a small cantilever length-to-web depth ratio. Based on parametric studies, profile 2 is revised with the cantilever length-to-web depth ratio for wide applications. Finally, comparisons of vertical temperature gradients are made between the investigated composite girder and the recommendations in Chinese Specification.

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.