Study On The Mechanical Properties Of Composite Box Girders With Corrugated Steel Webs And Longitudinal Horizontal Diaphragms

In recent years,long-span composite box girder Bridges with corrugated steel webs have been developed continuously.However,with the continuous increase of bridge span,the corrugated steel web at the root of box girder is prone to instability because of its large height.The buckling behavior of corrugated steel webs can be improved by adding longitudinal concrete horizontal baffles into composite box girders.At present,the research and application of corrugated steel web composite box girder with longitudinal horizontal partition are relatively few.Therefore,it is necessary to systematically study its mechanical properties.In this paper,the bending,shearing and deflection effects of corrugated steel web composite box girder with longitudinal horizontal baffles are systematically studied by using the finite element method,which provides a theoretical basis for understanding the mechanical properties of the new composite box girder.The main research contents are as follows:(1)Based on the finite element model of uniform section composite box girder,the bending performance of composite box girder is studied.The analysis shows that corrugated steel webs still have the folding effect,and the bending contribution of corrugated steel webs can be ignored.The bending strain distributions of lining concrete,longitudinal horizontal diaphragm and concrete roof and floor approximately satisfy the assumption of quasi-plane section.(2)Based on the finite element model of uniform section composite box girder,the shear performance of composite box girder is studied.The analysis shows that the shear force of composite box girder is mainly borne by corrugated steel webs and inner concrete.Due to the effect of the lining concrete,the shear stress of corrugated steel webs is distributed in sections along the webs.Concretely,the shear stress of corrugated steel webs is evenly distributed in the height range of pure steel webs without lined concrete,and decreases in the height range with lined concrete.The effect of shear deformation on the deflection of the composite box girder is between the corrugated steel web girder and the concrete web girder.The shear stress distribution,shear stress magnitude and shear ratio of corrugated steel web are related to the thickness of lining concrete,the height ratio of lining concrete to web and the thickness of steel web.(3)Based on the finite element model of uniform section composite box girder,the deflection effect and influencing factors of corrugated steel web composite box girder with longitudinal horizontal partition are studied.The analysis shows that the torsional stiffness of composite box girder can be improved effectively by setting longitudinal horizontal partition and lining concrete,and the normal and shear stress caused by torsion and distortion can be reduced.The increase coefficients of partial load displacement,normal stress and shear stress are mainly related to the width-span ratio,height-span ratio and the ratio of suspended wing of the composite box girder,while other geometric parameters have relatively little influence.(4)Based on the actual engineering background,the finite element model of the continuous rigid frame bridge with corrugated steel webs with longitudinal horizontal partitions was established to study the bending and deflection load performance of the composite box girder bridge with corrugated steel webs with longitudinal horizontal partitions.The analysis results are consistent with those of finite element model of uniform section composite box girder.