Study On The Flexural Performance Of Steel Grid-UHPC Composite Bridge Deck

Steel-concrete composite structures are increasingly widely used because they can make good use of the advantages of the two materials.As a cement-based composite material with ultra-high strength,toughness and durability.Ultra-high performance concrete has been paid more attention in bridge engineering field.A new steel grid-UHPC composite bridge deck is proposed in this paper,its flexural performance is studied through numerical simulation and theoretical analysis,The main research work and results are as follows.(1)Study on the design and construction of steel grid-UHPC Composite bridge deckA new type of bridge deck is put forward: steel grid-UHPC composite bridge deck,which consists of Ultra-high performance concrete and steel grid members,corrugated steel sheets,reinforcing mesh and wearing surface laid over the concrete.The design structure and construction scheme of the new composite bridge deck applied to multi-girder steel plate composite beam bridge and large crossbeam composite beam bridge are proposed.(2)Study on bending performance of steel grid-UHPC composite bridge deckThe numerical simulation of multi-girder steel plate composite beam bridge and large crossbeam composite beam bridge is carried out by ANSYS.Combined with the influence line of stress,the load effect of composite bridge deck under dead load and vehicle live load and wheel load stress influence range are studied.The results are as follows:(a)The results show that,for the composite bridge deck perpendicular to the driving direction,the load outside two adjacent main girders has almost no effect on the stress of the mid-span bridge deck between the two main girders,and the load outside the two adjacent spans of a main girder has no influence on the stress of the bridge deck directly above the main girder.The contribution of the load more than 6 times the spacing to the stresses can be ignored.(b)For the composite bridge deck parallel to the driving direction,When the load is only applied on the bridge deck between the main beams(outside of the main beam),obvious longitudinal and transverse bridge stresses will be generated from each concern.(c)The contribution of the load with transverse distance over 6 times the spacing of the slabs to stress of the bridge deck is negligible.The load outside two adjacent cross beams has no contribution to the stress of the mid-span bridge deck between the two cross beams.The load outside the two adjacent spans of a cross beam has no influence on the stress of the bridge deck directly above the beam.(3)Research on simplified calculation method of steel grid-UHPC composite bridge deckFor the composite bridge deck perpendicular to the driving direction,the structural internal force distribution of the bridge with span of 15-30 m,spacing of steel 300-500 mm,span of the bridge deck between main beams 2-4 m,and span of cantilever slab 1.0-2.0 m is studied through the numerical calculation.For the composite bridge deck parallel to the driving direction,the structural internal force distribution of the bridge with span of 17.5-31.5 m,spacing of steel 300-500 mm,span of the bridge deck between cross beams 3.5-4.5 m are studied.Based on the idea of load diffusion angle,a load distribution width method suitable for simplified calculation of internal force of steel grid-UHPC composite bridge deck is presented,the diffusion angle which determines the width of load distribution is obtained by numerical calculation.Based on the theory of plasticity,A simplified formula for calculating the flexural capacity of the normal section of composite bridge deck is established,which can provide a reference for the engineering design of the structure.(4)Flexural capacity and parameter analysis of steel grid-UHPC composite bridge deckThe nonlinear finite element simulation of steel grid-UHPC composite bridge deck is carried out by means of ANSYS.The mechanical properties of steel grid-UHPC composite bridge deck,reinforced concrete deck and corrugated steel-concrete composite deck are compared.The effects of concrete strength,thickness of concrete deck,steel strength and section steel type on bending performance of composite deck are studied.The results are as follows:(a)the new composite bridge deck can further reduce the dead weight and improve the flexural bearing capacity and structural stiffness.(b)Increasing the strength grade of concrete,the thickness of concrete deck,the size of section steel and the steel strength grade can effectively improve the bending performance of bridge deck.And increasing the size of section steel has the most significant effect.