Study On Stability And Design Optimization Of Long Span Steel-Arch-Frame Concrete Composite Arch Bridge For Whole Construction Process

The steel-arch-frame concrete composite（SAFCC）arch bridge springs out in recent years gradually,it is a new kind of bridge which combines the advanced construction technology for steel arch and mechanical properties of the steel-concrete combined structure.Stability should be focused.This paper is set in a project of a SAFCC arch bridge which is on the plan.Utilizing three kinds of the finite element anal ysis model s—MIDAS/Civil to establish the model s of the SAFCC half-through arch bridge.Results shows that it is more suitable for the model 2,better with construction,which tying more elastic element on the cross section of the arch rib than the model 1 which tying little.Model 3 which adopting composite section is much different from the other 2models.That means it should be abandoned.And then,taking nonlinear effect into consideration during the whole construction,putting bar’s local stability and arch’s global stability as entry point,to check the bearing capacit y and stability of the arch bridge in each construction phase with model 2.The results show that:local stability of kinds steel bars of the arch bridge’s satges are within the limits of the check formula.However,globle stability of the partial stages don’t meet the specification requiremengts,which integeral stability coefficients should be bigger than 4.According the existed problems,on the one hand,taking steel bar of number9^#section properties as viarate to parametric analtlize without changing the pouring sequrnce.Then taking nonlinear effect into consideration,results show that:1 in the stageC₀,it is non-significant to improve the arch globle stability by changing the properties of the section of 9^#,on the contrary,stability will be decreased if the area increases too much.2 in the stage of rib pouring,the stability will increase along with the area expan.On the other hand,proposing 7 another pouring scheme without changing arch section propert y,the results show that:the new scheme of pouring sequence is more suitable than the origin scheme,especially for scheme 3.Besides,based on the pre-load parametric analysis,we also find that:it is more efficient to reduce the impact of deformation to forming concrete than the old ways b y using constant pressure method during construction.