Experimental Study Of Temperature Effect On Prestressed Concrete Box Girder

Sunlight effect on box girder temperature effect is obvious, concrete beam bridge inthe sunshine for more than10hours in the summer, and the thermal conductivity of theconcrete is small, concrete surface and internal have bigger difference in temperature,due to the constraints to produce concrete temperature stress, when the temperaturestress is larger, which will lead to the crack of concrete.Concrete temperature effect mainly has three kinds of calculation methods, themethod of structural mechanics, thermal elastic mechanics method and the finiteelement analysis method, Structural Mechanics method is used in our country"Code forDesign of Highway Reinforced Concrete and Prestressed Concrete Bridge andCulverts", researches show that the results calculating in this method have significanterrors. Thermal calculation method considers the lateral temperature difference effecton beam strain, calculation results based on the thermal elastic mechanics is muchaccurater, but complex and not practical. In general, the high temperature side instructure, temperature difference will cause structural tension, temperature stress ofconcrete beam bridge is the main reason of cracking. In general temperature load,temperature stress will not lead to the crack of concrete, By making sure the mostadverse temperature gradient and the most disadvantageous position in the concretebeam, Concrete cracking caused by temperature stress can be avoided, on thisfoundation, improving the tensile strength of concrete or initial compressive stresscombining with the concrete structure design principle.The prestressed concrete box girder is the research object, observe the box girder inartificial light exposure through experimental, natural cooling process of temperaturefield, thermal stress, displacement,the variation law is summarized, and use the finiteelement analysis methods to simulate the temperature field and temperature stress. Thispaper makes suggestions to the specification which is insufficient, make the calculationsmore convenient and practical. Finally, four results caused by the standard formula,finite element model, test, the calculating method put forward in the paper werecompared and analyzed.The research results has a major direct effect on design, construction and operation.