Simplified Method to Calculate Average Cross-Section Temperature of Small Box Girder under Extreme Climate Conditions

Temperature variation can trigger longitudinal expansion and contraction deformation of the main girder of concrete bridges. To accurately predict the deformation, methods to calculate the average cross-section temperature of the main girder of bridges of such type were studied. A finite element model was established by MIDAS, taking a concrete small box girder bridge as the prototype bridge. The temperature field of the bridge was simulated and the peak average cross-section temperatures of the small box girder under extreme climate conditions were calculated. Two simplified methods to calculate the average temperature of the girder are proposed, one taking into account the peak ambient temperatures and the maximum daily solar radiation (Method 1) and the other considering the peak average daily temperatures on a monthly basis and the maximum daily solar radiation (Method 2). The results indicate that the finite element model built can accurately simulate the actual temperature field of the structure. It is suggested that the peak average cross-section temperature under extreme climate conditions be used to predict the main girder longitudinal expansion and contraction deformation of concrete bridge triggered by temperature variation. The peak average cross-section temperature of small box girder is in positive linear relation with the peak ambient temperature. Method 1 can generate accurate prediction, but a little complex. For the ease of calculation, Method 2 is a better choice, but the accuracy is not as good as Method 1.