The Research Of Shear Lag Effect About Box Girder Bridge With Corrugated Webs

The box girder bridge with corrugated steel web is a new bridge type.Replace the concrete web with corrugated steel web,which not only decrease the bridge weight,but also bring into full play the mechanical properties of various materials for the reason that the top and bottom plate of concrete mainly bearing bending moment and axial force,while the web mainly bearing shear force on the force.The paper mainly analyzed the shear lag effect about simply supported box girder bridge with corrugated steel webs from theoretical derivation and finite element analysis.And the result intends to provide the reference resources for the bridge design.Firstly,the shear lag coefficient formula about simply supported box girder bridge under the uniform load and concentrated load could be deducted by energy variational method.In the derivation process,the strain energy of each part about the box girder bridge with corrugated steel webs was analyzed on making proper simplification.During the formula derivation,the bending analysis could neglect the web bending and only consider the influence of the upper and lower wing.The next job was to select the finite element software ANSYS to conduct numerical simulation about the shear lag effect of the bridge to analyze the factors affecting shear lag effect of box girder.The calculation results showed that the width span ratio was the most important factor that affects the shear lag effect of box girder bridges with corrugated steel webs in all the factors.With the decrease of the width to span ratio,the shear lag coefficient of box girder bridge with corrugated steel webs increased greatly.The effect about suspension ratio to the shear lag effect of box girder is small.With the increase of the suspension ratio,the shear lag effect of box girder under concentrated load increased slightly.The variation of the top plate thickness had little effect on the shear lag effect of box girder.But it was necessary to try to keep the thickness of the top plate and the bottom plate thickness not differing too much.Otherwise,it would cause the increase of shear lag coefficient.The aspect ratio could not be considered as the main factor relative to several other factors when it came to the influence to shear lag effect on box girder.For web,the length of corrugated steel webs and the change of folding angle had small effect to shear lag effect of box girder.But it was important that the thickness of the web should not be too small,which would cause shear lag coefficient of box girder increasing,especially in concentrated load.Therefore the thickness of the web was reasonable for this kind of bridge designFinally,the shear lag effect of the box girder bridge under different working conditions was analyzed.The results was that when the concentrated load moves along the span of the box girder,about 1/5 of the span of the box girder,The shear lag coefficient of the load section had increased suddenly.Therefore,when carrying out the stress analysis of this bridge,only considering the load in cross was not enough.Secondly,Lateral displacement of load and adverse effect of partial load had a great influence on the shear effect of the bridge,which should be paid enough attention to the design and stress analysis of the bridge.