Abstract
Temperature variations in the girder at two cross-sections of a long-span prestressed concrete box girder bridge (PCBG) were analysed based on measured data. The results show that the temperature distribution in the concrete box girder (CBG) is strongly influenced by its size, and the temperature distribution in the girder changes along the longitudinal direction of the bridge. To clarify the temperature distribution in the long-span PCBG bridge, a two-dimensional (2D) temperature prediction model, validated by the measured data, was proposed, and the effect of the girder size on the temperature distribution of the CBG was studied using the model. Based on the results of the studies, simplified vertical and transverse temperature gradient models that could consider changes along the longitudinal direction of the bridge were proposed and validated by using the measured data and three-dimensional (3D) mechanical finite element model (FEM) of the bridge. Then, the deformations and stresses derived from the proposed temperature gradient models and the models according to different codes were studied and compared. Finally, conclusions and recommendations for future bridge design are provided.
Highlights
Long-span prestressed concrete box girder bridge (PCBG) bridges are generally built in open areas, and they are inevitably influenced by environmental thermal loads
For design purposes, simplified vertical and transverse temperature gradient models that can consider changes along the longitudinal direction of the long-span PCBG bridge were proposed on the basis of the results described earlier. e proposed vertical temperature gradient model is shown in Figure 17(a), and the notations are defined as follows
From the results presented in this paper, the following conclusions are obtained: (1) e critical temperature gradients in the girder all occurred on sunny days after a substantial warming trend for several days. e temperatures in the deck along the longitudinal direction of the long-span PCBG bridge were almost the same
Summary
Long-span PCBG bridges are generally built in open areas, and they are inevitably influenced by environmental thermal loads. The bridge temperatures along the longitudinal direction are usually recognized as constant, so it is valuable to study the temperature gradient and its effect on long-span PCBG bridges considering the changes in its cross-section. With regards to this need, the measured temperatures in a long-span PCBG bridge were analysed. A 2D temperature predicting model and a 3D mechanical FEM, validated by the measured data, were used to analyse the temperature gradient and its effect on long-span PCBG bridges. Vertical and transverse temperature gradient models that could consider the changes along the longitudinal direction of the long-span PCBG bridge were proposed and validated. Conclusions and recommendations for future bridge design are provided
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