Study On Mechanical Properties Of Steel-UHPC Composite Bridge Deck With Wet Joint

Orthotropic steel deck(OSD)is widely used in long-span bridge construction due to its characteristics of lightweight,high strength,and convenience in construction.A lot of practices show that OSD has two common diseases: fatigue cracking and pavement damage.The steel-UHPC composite bridge deck system can effectively solve these two common OSD diseases,which consist of ultra high performance concrete(UHPC)and steel bridge deck through shear connectors.In addition,the composite structure can reduce the number of welds in OSD and prevent fatigue cracking.A field bridge(Xijiang Bridge)in Foshan,Guangdong Province,adopts the steel-UHPC composite bridge deck.It sets the longitudinal stiffening open ribs on the top of the steel plate,rather than the bottom of the steel plate in OSD.UHPC is cast on the steel plate to form a steel-UHPC composite bridge deck system.The steel-UHPC composite beam segments are prefabricated in the factory and assembled on site.Two segments are connected through wet joints.The mechanical properties of wet joints in steel-UHPC composite slabs affect the overall mechanical properties of the entire beams.The wet joint is damaged,which affects the durability or safety of the structure.In this regard,this paper is to study the mechanical properties of the steel-UHPC composite bridge deck with wet joint.The main work can be described as follows:(1)Based on Xijiang Bridge,this paper conducts some experiments,including four steel-UHPC composite bridge slabs(with wet joints)and one integrated steel-UHPC composite bridge slab(without wet joints).Those specimens were tested under the positive bending moment.The results show that the wet joints are not weak zones in the steel-UHPC composite bridge slab.In addition,different curing methods for wet joints and the length of the wet joints have no effect on the ultimate bearing capacity of specimens.(2)The finite element models of the specimens with wet joints are established using ABAQUS.In those finite element models,three types of wet joint interfaces are investigated: binding constraint,Coulomb friction model and cohesive force model.It is found that the Coulomb friction model can give the best results.The parameter analysis with the finite element model shows that the dovetail angle has no effect on the bending stiffness and ultimate bearing capacity of specimens.Increasing the thickness of the UHPC layer and steel plate can effectively improve the bending stiffness and ultimate bearing capacity of steel-UHPC composite bridge slabs with wet joints.(3)The whole bending process of steel-UHPC composite bridge slabs with wet joints is analyzed,and a simplified formula for calculating the ultimate bending capacity is established.It has shown that the calculated results are in good agreement with the test values.Based on the experiment results,the formula for calculating the short-term flexural stiffness given in the Code GB50010–2010(in China),is modified,for calculating the stiffness of steel-UHPC composite bridge slabs with wet joints.The analysis shows that the theoretical calculation results obtained by the modified stiffness calculation formula are in good agreement with the test value.