Shear-lag Effect of Concrete Box Girder with Simply Supported Butterfly Web
To study the distribution of shear-lag effect of butterfly web concrete box girder,the shear-lag effect of butterfly web concrete box girder was studied from 3 aspects of experimental study,finite element simulation and theoretical derivation.The variations of shear-lag effect in the solid web and hollow web of box girder were studied by designing and fabricating the model of simply supported box girder with butterfly web and conducting the static loading test.ABAQUS finite element model was established,which was consistent with the test conditions.The spatial distribution of shear-lag effect of box girder with butterfly web under centralized and distributed loads was obtained by utilizing the data analysis and processing capability of finite element.Based on the principle of cross-section equivalence,the calculation method for inertia moment at hollow web of box girder was proposed.Combining with the energy variation method,the shear-lag effect calculation formula for box girder with butterfly web was set up.The formula was compared with the test results and finite element results to verify the accuracy.The result indicates that the longitudinal stresses in the top and bottom plates of box girder with butterfly web are positively distributed.The shear-lag effect on empty web is larger than that on solid web of box girder with butterfly web.The spatial distribution of shear-lag effect of box girder with butterfly web under different loads is that along the girder length,the shear-lag effect is larger on the pivot section and mid-span section of girder;along the width of girder,the shear-lag effect is larger on the section at intersection of web and the top plate;along the width of girder is larger at the intersection of top and bottom plates.The theoretical formula obtained by using the variation method shows that the error between the longitudinal stress value with variation method and the test value is from ―2.4%to 7.4%under the centralized load.The error between the longitudinal stress value with variation method and the finite element is from ―2.7%to 3.8%under the uniform load.That verifies the accuracy of formula,and provides the theoretical basis for the butterfly web box girder design.
bridge engineeringshear-lag effectenergy variation methodbutterfly webfinite element method
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