Research On Shear Behavior Of Connections Of Steel-UHPC Composite Deck

The current steel structure bridges in China are highly prized in bridge construction industry,for which it has been rapid developed.But due to the traditional asphalt pavement is so flexible that it can just provide little stiffness on orthotropic steel deck.So under the long-term heavy traffic action,steel deck will prone to arising fatigue cracking.On the other hand,the cracking of steel bridge deck will further induce many kinds of diseases,such as cracking and delamination.The cause of those diseases is the lacking of rigidity of steel bridge deck structure.The steel-UHPC composite deck structure is an effective method to improve the rigidity of the steel bridge deck and solve the common diseases of the steel bridge.Because of the high strength and high toughness of UHPC,the thickness of UHPC layer in steel-UHPC composite bridge deck is very thin(generally less than 60mm),the ratio of length to diameter will not meet the requirements of our specification.Based on the above reasons,in order to exploring the application feasibility of short stud and other connections in steel-UHPC composite deck structure,this paper study the corresponding shear performance of channel steel,steel opened-ring and short stud connectors of steel-UHPC composite deck structure.(1)The stress mechanism,failure mode and shear capacity of channel steel connector of steel-UHPC composite bridge deck structure are studied by the method of push-out test and finite element analysis.The test specimens are divided into two groups according to whether arranging reinforcement mesh.The test results show that the failure mode of two groups channel steel specimens are channel steel’s web break;the arrangement of reinforcement mesh can effectively improve the control of development of crack,but it almost has no influence on the ultimate bearing capacity.The finite element simulation is in good agreement with the experimental load-slip curve,and the finite element method is used to reveal the stress mechanism of the channel connector of steel-UHPC composite deck structure.(2)The stress mechanism,failure mode and shear capacity of the new steel opened-ring connector of steel-UHPC composite bridge deck structure are studied by the method of push-out test and finite element analysis.The test specimens are divided into two groups according to whether arranging reinforcement mesh.The experiments showed that the failure mode of two groups steel opened-ring specimens are the up-semi-ring sheared off and below-semi-ring pulled out;two group steel opened-ring specimens have excellent ductility;the arrangement of reinforcement mesh can greatly improve toughness and stress performance of the structure,but it almost has no influence on the ultimate bearing capacity.The finite element simulation is in good agreement with the experimental load-slip curve,and the finite element method is used to reveal the stress mechanism of the steel opened-ring connector of steel-UHPC composite deck structure.(3)The stress mechanism,failure mode and shear capacity of the short stud connector of steel-UHPC composite bridge deck structure are studied by the method of push-out test and finite element analysis.The test specimens are divided into five groups according to the stud diameter(10mm,13mm,16mm)and stud length(25mm,35mm,45mm).The test results shows that the specimens’ ultimate bearing capacity and shear stiffness will increase with stud diameter’s increasing,and it shows a linear relationship between bearing capacity and the stud diameter,but with stud diameter’s increasing,the increase rate of shear stiff&ess gradually slowed down;the bearing capacity of specimens with stud length increased exponentially,while the specimen shear stiffiness with stud length show a regularity that increased first and then decreased.The finite element simulation is in good agreement with the experimental load-slip curve,and the finite element method is used to reveal the stress mechanism of the short stud connector of steel-UHPC composite deck structure.