Thermal gradients in concrete box girders

In this study, a three dimensional thermal analysis using the Finite Element method was carried out to assess the heat conduction in deep concrete box-girder bridges taking in to accountthe prevailing conditions like ambient temperature, solar radiation incident and the velocity of the wind. The temperature distributions and differentials arising from the three dimensional Finite Element model were compared with the site measurements that were available in literature. The current Finite Element analysis has predicted the concrete temperatures effectively with maximum temperature errors ranged from 0.17oC in the North web to 1.71oC in the top flange. The three dimensional Finite Element model was used with meteorological data to carry out numerical measurements of temperature distributions in order to compute thermal gradients in deep concrete box-girders under the summer conditions of Gaziantep, Turkey. The proposed model was then used to study the effect of the cross-section geometry on the temperature distributions and the temperature gradients in deep concrete box girder bridges. The analyzed geometrical parameters are the thickness of the top slab, the thickness of the bottom slab, the width of the cantilever wing and the depth of the box girder. Moreover, some observations related to the vertical and transverse temperature gradients were presented. Key words: Air temperature, deep box-girder, finite element thermal analysis, solar radiation, temperature gradient