Temperature Gradient Analysis Of Long-span Prestressed Concrete Box-girder Bridge

With the large number of prestressed concrete bridge construction, many problems appeared in the process of bridge construction and operation.The primary factor is the cracks caused by temperature stress, therefore, the temperature distribution of long span prestressed concrete bridge and the temperature effects of the bridge have attracted attention of bridge experts and researchers at home and abroad.Combined with a 150m long-span prestressed concrete box-girder bridge,this paper discusses the temperature effects under all kinds of temperature gradient model,the main work are as follows:1.Based on the temperature gradient patterns of the China's new and old highway norms, the British standard, and the New Zealand standard, the FEM model of the main bridge during operation phase was created by MIDASC/IVIL sotfware in order to simulate the temperature field during operation phase. Compared all models of temperature gradient effect on the degree of influence of the main bridge under live loading with each other, the calculating results shows that the temperature effect of China's new highway norms is slightly larger than the other standards, and the temperature effect has similar effectiveness and function with living load,so the temperature effect is one of important factors which influences the impact of box-girder cracks and structural safety.2.Find out the change law of temperature field in the box girder section by analyzing the temperature data at various measuring points. Based on the China's current highway norm, redistribution of the temperature field along the box-girder section is derived under the gradual increase by 1℃of the temperature gradient.3.Based on the gradient model under the redistribution of temperature field, the FEM model of a 150m span prestressed concrete box-girder bridge was created to do the temperature sensitivity analysis. And the result shows that temperature stress approximately changes by a fixed value with the equivalent gradient change. In other words, the stress variation approximately have a linear relation to the temperature changes.By calculating and analyzing the temperature effect during the all kinds of temperature gradient of long-span prestressed concrete box-girder bridge, the result shows that the temperature stress has a significant impact on the mechanical behavior of box-girder, so a reasonable temperature gradient model is the premise of correctly analyzing the box-girder's temperature effect.