Experimental Study On The Temperature Effect And Shear Lag Effect Of P.C. Box Girder

Because of the good mechanical properties of space P.C box girder it have been application in vrious types of bridges.A lot of bridge's flexivity is bigger than design value.For it, a series of experimental and analytical research of the concrete box girder have been investigated in this paper. These include temperature field and temperature effect of Concrete box girder; taking the repeated action in the temperature difference on box girder and the shear lag effect of box girder.Take the research of temperature field and temperature effect on box girder through artificially temperature increasing. According to the site collected temperature data, the paper brings forward the characters of the temperature field in box-beam, and the fitting gradient of PC continuous box beam that is the Chinese railway standard. According to the measured temperature field in the data set up finite element analysis model, analysis of temperature effects, and then the measured effect of temperature data and compared the results of the analysis, the two trends have been confirmed with a larger horizontal box and vertical tensile stress . Model of the largest cross-section temperature and the temperature coefficient with the time change, by controlling the heating time and heating power can effectively simulate the real circumstances of the concrete box girder and the effect of the temperature field. Through finite element analysis to explore the physical properties of the material on the hot box temperature fields and effects.Take the repeated action in the temperature difference on box girder through artificially repeated temperature increasing. The experiment also tests the vary of deflection of box girder with its dead weight and under prestressing force, the result of which is: the repeated action of temperature increasing can disharmonize the bottom strain of box girder, which may lead to the downwarping of box girder; the changing temperature has no obvious influence on the flexivity of simply-supported box girder.The shear lag phenomenon has been confirmed based on the experimentalstudy of flexural behavior of reinforced concrete box girder. The experimental value of equivalent calculating coefficient of flange width has been obtained at elastic stage.The calculated formulae has been proposed about equivalent calculated coefficient of flange width at the middle span of simply-supported concrete box girder in elastic state.