Single-box Double-chamber Beam High-speed Railway Tied Arch Bridge Shear Lag Effect

With the rapid development of economic construction at home and abroad,the people's living standards are rapidly improving,and the aesthetics of the “applicable,economical,safe,and beautiful” principle of the bridge design have received more and more attention.Nowadays,all types of bridges are not only used as engineering entities.Existence,and also as a spatial art structure displayed in social life.In recent years,various types of arch bridges have been designed both at home and abroad,on the one hand to enrich the aesthetics of bridges,and on the other hand to promote the rapid development of bridge construction.In this paper,the principles and methods for the simplified analysis of the box girder segment are obtained according to the conditions of mutual equilibrium between the segment and the whole.Taking the simply supported beam and continuous beam under vertical load as an example,the simplified section analysis method is used to calculate the stress values??of the selected special section roof and floor under vertical loads,and the cross section obtained from ANSYS is used.Comparing the stress values ??of the top plate and the bottom plate,the results can be obtained.The simplified segment analysis method agrees well with the stress values ??obtained from ANSYS,so the simplified segment analysis method is applied to the shear lag effect of the simply supported beam and continuous beam under vertical loads.Is applicable.In this paper,the finite element model of the full bridge was established based on the Yinxi High-speed Railway Tied Arch Bridge.The study of the shear lag effect of the main girder of the tied arch bridge and the analysis of the influencing factors of the shear lag effect parameters were carried out.The work done in this paper mainly includes:(1)Based on the static equilibrium conditions of the beam section based on the general beam theory,a simplified analysis method for the box-girder shear-lag segment is constructed based on the mutual equilibrium condition between the segmental and the overall static balance,and the box girder is analyzed with it.Lag effect.Combined with the model of the concrete box girder under the concentrated force,the stress values ??at different positions of the top and bottom slabs of the special section were calculated by this method,and compared with the stress values ??obtained from the finite element model,the stress variation trend of the two beams was in good agreement.Verify the feasibility of this method.The analysis method of box girder segment proposed in this paper is suitable for the shear lag effect of simply supported beam and continuous beam under vertical force,and it can also be applied to simplified analysis of shear lag of complex box girder structure.(2)Based on the Yinxi high-speed tiebar arch bridge project,after the finite element model of Midas Civil and ANSYS was built,the stress values ??obtained by the finiteelement method and the simplified segment analysis method were compared to obtain the shear lag effect of the tied-arch bridge..The shear lag effect of the single-box double-cell box girder top plate in the bridged state of the tied-arch bridge is significant,especially in the mid-span position,where the maximum stress in the cross-section exceeds the average stress by 16%.The shear lag effect of box girder bottom plate is not obvious compared with that of roof plate.The maximum shear lag coefficient is within 5%,which is consistent with the structural characteristics of wide flange and narrow bottom plate of box girder structure.(3)By changing the thickness of the top plate,the thickness of the bottom plate,the thickness of the web,and the presence or absence of pre-stressing factors,a finite element software model ANSYS was used to establish several finite element calculation models for the full bridge of the Yinxi High-speed Railway Tied Arch Bridge.The influence of these parameters on the shear lag effect of tied arch bridges is obtained.Some important conclusions can be referenced in the subsequent design and construction.