Analysis On Shear Lag Effect Of Composite Box Girder Bridge With Corrugated Steel Web And Steel Bottom Plate

The corrugated steel web composite box girder bridge is a new type of steel-concrete composite bridge structure.Compared with traditional prestressed concrete box girder bridges,it can greatly reduce the weight of the box girder and save the cost.As more and more corrugated steel web box girder bridges have been constructed in recent years,girder bridges with steel plates as their base plates have appeared.With the corrugated steel web composite box girder bridge with a slab different from the general concrete slab,it is necessary to analyze the shear lag effect of this type of bridge.This paper will analyze the shear lag effects of such bridges.Steel floor corrugated steel web combined box-girder bridge structure is characterized in that the material of the web and floor plates is steel,and only the top plates is concrete.Therefore,the method of analyzing the shear lag effect of this type of bridge is different from the corrugated steel web composite box girder bridge of ordinary concrete floor plate.When analyzing the shear lag effect of this kind of box girder bridge,it is necessary to deal with different materials of cross section first.Then,the width correction coefficient of the cantilever plate and the shear effect of the corrugated steel web are considered.Finally,the deflection,stress and shear lag coefficient expressions of the simply supported box girder with corrugated steel webs under different load forms are derived based on energy variation method.Combined with actual engineering,firstly calculate the deflection,stress and shear lag coefficients of the mid-span section of the bridge under a single load and live load,and then extract the deflection and stress data through the establishment of the ANSYS model and the finite element calculation.By comparing the calculation results of the two methods,verifying the accuracy of the analytical method and comprehensively analyzing the shear lag effect of the bridge.It can be seen from the calculation results that the analytical calculation results and the finite element calculation results are in good agreement.The shear lag effect is most obvious at the intersection of the web and top plate.Under the single load of the same size,the shear lag effect of the box girder under the concentrated load is more significant than that of uniform load.Compared with dead weight,the shear lag effect of box girder bridge under live load is more obvious.The finite element method is used to explore the influence of different factors on the shear lag effect of box girder.The calculation results under the control of a single variable show that the change of corrugated steel web structure has a very small effect on the shear lag effect of box girder.But the overall size has a greater effect on the shear lag effect of box girder.In the overall size of the box girder,the thickness of the upper wing panel and the width-span ratio have the most obvious effects on the shear lag effect.The wider the box beam,the thicker the upper flange plate,the more pronounced the shear lag effect of the box beam.It is found through calculation that the shear lag effect of box girder is weakened when diaphragm installed.Therefore,in bridge design,the shear lag effect of the corrugated steel web composite box girder bridge can be weakened by setting diaphragm.