Thermal Stress Behavior And Arithmetic Realization Of Bridge Structure

After a concrete girder bridge has been constructed, the temperature on the bridge surface change sharply, but the inner temperature of the bridge structure change slowly because of low heat exchange coefficient of concrete material. So, the temperature distribution on the sections of the bridge structure isn't uniformity, and that establish nonlinear thermal stress. In past forty years, several prestressed concrete girder bridges had been severe damaged, and many studies have indicated the main factor of the cracking in bridge structure is thermal stress. Therefore, in the design of concrete girder bridge, the effect of thermal stress must be considered.In this thesis, the characteristic of the temperature load is been introduced. Considering the change of environment, the temperature load can be classified to three types: solar radiation, temperature falling suddenly and yearly temperature variation. By the methods of Fourier heat transfer theory and finite element, the temperature load distribution is analyzed, and basic equations are formed.Based on the theory of solving thermal stress of bridge structure, the formulations of thermal self-stress under nonlinear temperature gradient condition and thermal inferior stress in hyperstatic structure have been put forward. The module of calculating thermal stress has been designed, using second development utility of the developing platform, the technique of structural simulation for entire bridge and visual C++ utility.At last, two examples as a two-span continuous concrete T-girder bridge and a multi-span continuous concrete box girder bridge being involved, the thermal stress is been calculated by the universal engineering method and the method in the thesis. Comparing two results, internal force of the structure and stress of the sections are very close, that indicate the calculating method in the thesis is exact and convenient.