The Research On Side Span Closure Scheme Of Grider Bridge With Rigid Frame-continuous Combination System

As the development of traffic construction in west mountain areas of ourcountry,the girders bridge with rigid frame-continuous conbination system isbecoming more and more widely used due to its advantages of length and mechanicalbehaviors.Side span is always closured up by consol supports in the design.Butconsidering special geographical enviroment in mountain areas,according topractice,bridge engineer points out that the hanger is more suitable for site actualsituation than consol supports.in order to keep the structure safe at construction stageand finished stage,the difference of tress and aligenment after changing side spanclosure scheme must be verified previously.Based on Donglu viaduct on Yonglanexpressway,this paper created a finite element model and analyzed the effects ofchanging side span closure scheme:(1) This thesis discribed construction technology used while closuring up theside span,and presented load-bearing structrue for side span in detail.(2) Based on two different side span closure schemes,this paper comparedalignment and mechanical behaviors of bridge structrue at construction stage andorperation stage.Then analysised the reason for difference of stress and rechecked thestress and displacement of main grider under the combination for action effects whenthe side span was closured up by hanger.and its conclusions can provide a theorcticalreference forthe design and construction．(3) This paper calculated the stress of main grider after increasing counterweightand pretress loss to keep constructure safe in construction stage,then proposed thebest scheme for precious tension of closure steel strands to provide technical supportfor pratical constuction.The comparison of alignment and mechanical behaviorsbetween batch tension and single tension was carried out,based on that,some usefulsuggestions for reducing the mid-span vertical deflection was made.(4) Based on using hanger to closure up side span,this thesis analysised andcalculated three closure orders including design closure order,according tocomparison,the most suitable order was determined,its datas are of great guidingsignificance when the closure orders need to be determined for similar bridge types.(5) This paper analysised concrete shrinkage and creep action effects on stress infive years after the whole structrue is closed in diffrent orders,some valuable technical datas are provided for the research of shrinkage and creep secondaryinternal forces.