Experimental investigation on the temperature distribution of corrugated steel web box girders with and without encased concrete

The thermal stresses resulting from temperature gradients within the structural components of bridges significantly affect their durability. This research conducted a field study to monitor the structural temperatures and environmental parameters (consisting of air temperature, solar radiation, wind speed, and air humidity) for both sections of corrugated steel girder bridges with and without encased concrete. Data was collected at a frequency of 30 minutes, and the monitoring period lasted for 268 days. Based on the measured data, temperature prediction equations for corrugated steel web box girders considering the box-inside temperature and the normalized environmental factors at a moment were first proposed. The prediction accuracies of three moment-based formulae for measuring point temperatures were compared and temperature difference distribution models for box girders at different locations were proposed. The results showed that the consideration of air humidity did not significantly improve the prediction accuracy of the temperature at the measurement point. However, taking into account the box-inside temperature could significantly enhance the prediction accuracy (the coefficient of determination R 2 increased from 0.87 to 0.99). The accuracy of predicting the temperature difference in box girders using the daily maximum temperature difference was higher compared to using moment-based temperature differences (R 2 improved from 0.57 to 0.87). The encased concrete had significant effects on the vertical temperature difference of the corrugated steel web. The horizontal temperature difference was “U” shaped along the width of the top plate, while the concrete bottom plate showed a consistent temperature difference distribution.