Study On Thermal Effects Of Super Long-Span Concrete Arch Bridge With Cfst Stiffened Skeleton

Under the influence of solar radiation, temperature variation and other factors, the nonlinear temperature distribution may appear in the cross section of concrete bridges. Such distribution can induce thermal stress and temperature displacement. The thermal stress in bridge, which can reach to the same level with the stress induced by traffic loads, becomes therefore a significant reason of cracking and attracts a lot of attention. A simple calculation model is usually used in practical designs, and the temperature distribution patterns in current design codes are always based on the entire girder section. However, the section of the concrete arch bridge involved in this thesis is casted gradually; the temperature distribution and the structural system during construction are both different from those of the girder section completed. Consequently, it is worthy of a special study.Firstly, according to the solar physics and heat transfer theory, the influencing factors of temperature field are summarized and analyzed. The effects of solar radiation, convection heat transfer and radiation heat transfer can be equivalent to the increase of air temperature. Secondly, ignoring the longitudinal heat conduction along the bridge axis, a FEA model of temperature field of the entire girder section is established. Applying the equivalent air temperature to this model as boundary, the temperature field is numerically simulated, and the results are compared with practical codes. Then, based on the results of simulation, the transversal stress is analyzed with a plane strain element model and the longitudinal stress is analyzed with a spatial beam model. In addition, another model without stiffened steel tube is compared with the former model to demonstrate the influence of stiffened steel tube.Finally, following the construction method of the arch, the models corresponding to each construction stage are established, and the relative stress is analyzed. Based on the research, the anti-cracking measures are proposed.