Research On The Flexural Behavior Of Concrete Box Girder Oriented To Double-deck Traffic

The concrete box girder which realize double-deck traffic is based on theordinary concrete box girder，through increasing the section size, canceling theconventional diaphragm, making its roof andbottom plate become bridge floorsystem，and opening necessary holes in webs to meet the ventilation, lighting andfire protection requirements, so make the city bridge realize double traffic，andeffectively，relieve the congestion status of urban traffic in our country.Based onthe functional requirements and a certain proportion of the reduced-scale designedthe test model of concrete simply supported box girder which realize double-decktraffic,through experimental study and element analysis of the box girder modelunder three different loading conditions，Mainly study the Bending performanceof the box girder under double-uniform load. the main work and conclusion list asfollows:1.Based on grasp the bridge traffic situation of small、medium-sized citiesin our country,sufficient access to relevant literature and familiar with the relevantnorms,combined the advantage of box section, the single box three rooms andinclinedweb concrete box girder which realize double-deck traffic is designedaccording to city medium span48-meter-long bridges, the girder is7.4m high. Theupper deck is designed for two-way four-laneand there sidewalk, the upper deck is24.5meters wide; The bottom of the deck is designed for the urban two-lanelightrail public transport, The urban pipelines and cables can be arranged in the middleroom of the box girder, the bottom deck is13.2meters wide. Reduce the box girderbridge size according to the scale of1:6, Simplified the box girder test model asconcrete beam and slab structure,regard the roof and floor of the box girder astwo-way and single way concrete slab,the webs as simply supported beams, use theflat-slab theory of concrete frame structure design the roof and floor stiffeners andweb.2.Through test for the box girder model under three different loadingconditions，initially revealed roof strain distribution law of the concrete box girderwhich realize double-deck traffic under double loads from the test,the results showthat: Under double uniformly distributed load, the roof of cross-section of the boxgirder showed positive shear lag phenomenon. 3. ANSYS finite element model building, finite element analysis of thedeflection、roof and floor shear lag distribution was analysed and compared withthe experimental results,it show that the results agree well. Further analysis by thefinite element of shear lag effect was analysed,the results show that: the shear lageffect have great relationship with the location of the load; Under the same uniformloads conditions,shear lag effect of the mid-span section is minimum,the closer tothe bearing end of the beam the shear lag phenomenon is more serious; Under theuniformly load,when all the load was loadingon the roof,the shear lag effect is notobvious,when all the load was loading on the floor,the shear lag phenomenon ismore serious.