Thermal Effects on Curved Steel Box Girder Bridges and Their Countermeasures

Abstract

Owing to its light self-weight, low heat capacity and large thermal expansion coefficient, the application of the curved steel box girder bridge with small and medium spans has gained popularity for the construction of urban infrastructure. However, sun exposure could easily increase the maximum temperature difference at the bottom of steel box beam by 25°C. With the effect of nonuniform temperature field and overloaded vehicles, the edge inside the curved steel box girder bridge may be separated from the remaining structure, resulting in overturning. Thus, more attention needs to be paid in order to prevent the separation. In this paper, an overturning resistance analysis of a three-span curved steel box girder bridge located in Hangzhou, China was performed. A model was proposed based on the measurement of temperature field to the steel box girder. The separating displacement due to temperature variations was predicted and verified by the measurement results. As a result, changes in supporting reactions due to the effect of the nonlinear temperature field and self-weight and offset vehicle load were determined, and the overturning stability of the bridge was analyzed via the trial and error method. The balance weight method was employed to diminish the risk of overturning of bridges. Finally, the method proposed in this paper was applied to a bridge under construction, which results in an increase in stability safety factor from 0.63 to 2.58.