The Reasearch On High Speed Railway Precast Concrete Box Girders Hydration Heat Temperature Field And Its Effect

With the continuous development of economy and technology, the span and the tonnage of concrete box girder are increasing, high performance concrete is widely used in the bridge construction.However,due to the size of the box girder section is increasing, coupled with the application of high performance concrete, resulting in hydration heat of concrete temperature increased, concrete shrinkage and stress increased, the box girder surface cracks,thus making the durability of concrete structure has been greatly affected and harmful to the quality and normal use of the structure.Large tonnage precast concrete box girder due to cement hydration temperature field is the important cause leading to the cracks of concrete, however, domestic and foreign experts to the special study of its mechanism and causes is relatively few, the study of box girder and its effect on hydration heat temperature field is not enough.In summary,it can be known that the hydration heat temperature field of the large-span precast box girder and the analysis of its influence factor have considerable economic value and social benefit.Due to the influence factors of box girder concrete temperature field and its parameters of the complex and changeable, so this article will study combined with practical engineering, and gives the feasible measures of controlling concrete hydration heat, services for the precast concrete box girder construction.Based on Harbin-Dalian high speed railway prestressed concrete box girder precast construction as the background, first detailed exposition of box girder precast construction process to ensure that won’t because of construction problems influence the distribution of box girder concrete hydration heat temperature field.Then analyses the theory of concrete temperature field, and on this basis, using the ANSYS finite element analysis software, based on the theory of three-dimensional unsteady temperature field simulate hydration heat temperature field of precast concrete box girders of span 32 m, and compare the analysis of the obtained data and field measured data, and the factors affecting the temperature field distribution are studied.Research results show that using the method of numerical analysis can be more realistic simulation concrete hydration heat temperature field, according to the analysis results this paper puts forward some specific measures to control temperature cracks, and presents the concrete box girder hydration heat temperature field distribution important influencing factors.Full text takes practical engineering project as the background, using the temperature field theory and finite element analysis software ANSYS, according to the engineering actual situation,can be used in the engineering practice of precast box beam of water of heat temperature field and its effects.The results of this study for large concrete box girder prefabrication process hydration heat temperature monitoring to prevent temperature cracks provide a more reliable basis, has a certain theoretical value and high practical value.