Effect of sunshine temperature difference on multi-span continuous rigid box girder bridge

Abstract The deformation caused by the temperature gradient, when constrained, generates thermal stress, and solar radiation-induced thermal stress is a significant cause of cracking in many bridges. To investigate the influence of solar radiation on multi-span continuous rigid box girder bridges and assess the applicability of international bridge codes temperature gradient models in southwestern China, this study employs numerical simulations to analyze temperature and stress distributions in box girders. The maximum daily temperature difference in summer and winter was selected as the calculation case, and the influence of the pavement on the temperature gradient of the box girder section was analyzed in detail. The results indicate that the temperature difference on the top plate can reach up to 14 °C under a maximum daily temperature difference of 16 °C in summer, representing the most unfavorable vertical temperature gradient. The temperature gradient model specified in the Chinese bridge code most closely matches the calculation results in this study, followed by the British bridge code. If the shading effect of the flange plate on the web is ignored, the web will exhibit a transverse temperature gradient of 21.6 °C in winter. When the pavement is asphalt, the calculated value in this study closely matches the reference value from the Chinese bridge code. However, when the pavement is concrete, the calculated value exceeds the reference value by 14%. This suggests that applying the temperature gradient provided by the Chinese bridge code directly to southwest may be unsafe. The results of this study offer recommendations for improving the temperature gradient models in Chinese bridge code.