| Ultra-high performance concrete(UHPC)is a cement-based composite material with high strength,high toughness and strong durability.The combination of steel and UHPC forms a new type of composite beam structure,which greatly reduces the weight of the structure and is beginning to be used in long-span bridge.At present,there are many related researches on UHPC beam bridges,but few researches on steel-UHPC composite structures.This paper takes Foshan Fulong Xijiang Steel-UHPC Composite Girder Cable-stayed Bridge as the engineering background,and considers the influence of steel-UHPC interface slippage.The research on the static spatial performance of this bridge is carried out.The work is as follows:(1)A double-layer beam model considering the sliding effect of steel and concrete is established,and the validity and accuracy of the established double-layer beam model are verified by numerical examples.Using MIDAS software,the Fulong Xijiang cable-stayed bridge structure analysis model is established,and the longitudinal relative slip and static response of the girder under different load conditions are calculated and analyzed.The relative slip value of the composite girder interface of the cable-stayed bridge complies with the limit stipulations of the current code,and there is more surplus.Even if the shear studs in the composite girder are reduced by 50%,the changes of deformation and internal force in the girder are small.(2)Considering the long-term effects of concrete,the shrinkage and creep of the UHPC bridge deck using steam curing are very small,so the deformation of the girder is also small,the shrinkage and creep of the pylons and the side span prestressed concrete have a relatively large influence on the deformation of the girder.Considering the effects of slippage and shrinkage and creep at the same time,the vertical deformation of the girder increases.Considering the influence of UHPC bridge slab curing conditions and construction methods on the deformation and force of the girder,UHPC of high-temperature steam curing and choosing prefabricated assembly construction in natural curing conditions,and the overall benefits of storing the beam for 6 months are better.(3)The multi-scale finite element model of the girder structure was established by using ABAQUS software,and the normal stress distribution of the deck in the middle span and the pylons area under the second-stage dead load was analyzed and calculated,and the shear lag distribution of the deck was discussed.The shear lag effect of the deck near the middle of the span is more obvious than the pylons area(except the tower roots).The effective width coefficient of the deck in the mid-span area ranges from 0.63 to 0.89,and the bridge tower area(except near the root of the tower)is between 0.90 to 0.95.(4)Under live loads,the effective width coefficient of the deck in the pylon area is unchanged basically,and the effective width coefficient of the deck in the mid-span area varies slightly with different load conditions.The stress change of the deck in the mid-span area is basically not affected by the temperature and the settlement of the main tower.The deck is greatly affected by the temperature in the bridge tower area,the stress of the deck decreases when the temperature rises,and the stress of the deck increases when the temperature drops When the pylon settles,the normal stress of the deck far away from the pylons increases as a whole. |
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