The Research On Transverse Mechanical Performance Of The Assembled Variable Section Corrugated Steel Web Composite Box Girder

As a new type of composite structure,the composite box girder with corrugated steel webs has the advantages of clear force and beautiful shape,and is more and more widely used in bridge construction.The combination of precast segmental assembly technology and corrugated steel web composite box girder can shorten the construction period and improve the construction efficiency under the premise of ensuring the construction quality,which has broad development prospects.In recent years,with the development of composite box girder bridge with corrugated steel webs towards the direction of large span,multi-chamber and wide cantilever,the transverse force problem of bridge deck is becoming more and more prominent.In this thesis,the transverse mechanical properties of assembled composite box girder with variable cross-section corrugated steel webs are studied by means of model test and numerical simulation.The main research contents and conclusions are as follows:(1)A prefabricated variable cross-section composite box girder with corrugated steel webs and an integral box girder with the same parameters were designed and fabricated.Symmetrical loading and eccentric loading were carried out on the mid-span of the middle span and the mid-span of the side span of the two beams.Based on the numerical analysis,the single-point eccentric load failure test in the middle span was simulated to study the influence of the difference of construction methods in the elastic stage and the plastic stage on the transverse strain of the roof.1)In the elastic stage,the transverse strain distribution of the two beam roofs is basically the same.The transverse strain of the assembled beam roof is slightly larger than that of the whole beam,and the different construction methods have little effect on the transverse strain of the roof.2)In the plastic stage,the transverse strain distribution law of the two beam roofs is the same as that in the elastic stage.However,with the increase of the load level,the transverse strain growth rate of the assembled beam roof is obviously faster than that of the whole beam.The transverse strain difference between the two roofs gradually increases,and the difference of construction methods has a great influence on the transverse strain of the roof.(2)Based on the model test and numerical analysis,the effective distribution width of the bridge deck of the assembled variable cross-section corrugated steel web box girder is studied.The difference between the effective distribution width of the segmental beam and the whole beam is explored,and the effective distribution width of the bridge is corrected.1)Under the elastic loading condition,the effective distribution width of the assembly beam roof is slightly larger than that of the whole beam,and the maximum difference is not more than 10%.2)The calculated value of the effective distribution width of the roof is too conservative,which can be corrected by multiplying the calculated value of the current specification by a coefficient of1.3～1.5;3)In the plastic stage,the effective distribution width of the roof increases first,then decreases and then increases.The effective distribution width of the roof in the limit state is 1.19 m,which is more than twice that in the elastic state.4)The effective distribution width in the plastic stage can be appropriately relaxed on the basis of the elastic stage.For the design of the ultimate bearing capacity state of the structure,the effective distribution width of the roof before the yield of the steel bar is taken as the plastic value index.(3)The effects of web support stiffness,lateral loading position,transverse partition spacing and rubber layer thickness on the effective distribution width of the assembly beam bridge deck were discussed by ABAQUS software.The results show that: 1)The change of web support stiffness has little effect on the effective distribution width of the top plate.2)Different horizontal loading positions have a great influence on the effective distribution width of the top plate,and when the loading point is located between the middle web and the side web,the effective distribution width first increases and then decreases;When the loading point is located at the flange,the effective distribution width increases as the loading point moves towards the flange end.3)The effective distribution width of the top plate increases with the increase of the spacing of the diaphragm,and the change range is within 10%;The change in the thickness of the adhesive layer has little effect on the effective distribution width of the top plate and is negligible.