Thermal loads are not often considered during the design of steel box girders, but their influence can be quite important. When the thermal gradient within the steel box girders reaches considerable values, a number of other effects are influenced. High thermal gradients will reduce the cohesion of waterproofing layers and surface layers. Therefore, the quantification of the thermal loads acting on the system becomes essential. This is primarily done using detailed finite element models of steel box girders. Modelling all the thermal fluxes within this system, including solar radiation, radiation with the environment, mutual radiation, convective airflow, etc. it becomes possible to study the temperature variations on the bridge structure. The thermal loading is based on the actual revolution of the sun, while the bounds and the orientation angles are the result of a detailed calculation of the position of the sun. The same is true for the respective fluxes. All of these variations are studied along a one year period and this on hourly basis.
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