Vertical Temperature Gradient Test and Numerical Simulation of Steel Box Girders in Cold Regions

The vertical temperature gradient of steel box girders in cold regions is not stipulated in the relevant specifications of China. Therefore, a systematic and comprehensive study was necessary. The vertical temperature distribution characteristics of the web were analyzed on the basis of steel box girder temperature monitoring data for 1 year in a cold region to obtain a vertical temperature gradient model corresponding to the actual situations of cold regions, which was compared with the specification. The temperature field numerical model was verified using the measured data. The parameter sensitivity of the vertical temperature gradient was analyzed. Results show that the daily variation of the web temperature of a steel box girder in cold regions is similar to a sinusoidal curve. The temperature fluctuation range in summer is larger than that in winter. Moreover, the positive and negative temperature differences occur in summer and winter, respectively. The vertical positive and negative temperature gradients are in the forms of an exponential function and a broken line, respectively. The fitted vertical temperature gradient in this paper was basically greater than the specification. The span of boundary conditions of the numerical model was reasonable. The influence of parameters on the vertical temperature gradient ranks ranked as follows: bridge deck pavement thickness > radiation absorption rate > wind speed > coefficient of heat conductivity > specific heat capacity.