Study On Mechanical Properties Of Steel-UHPC Epoxy Toughened Interface For Steel Deck Pavement

The orthotropic steel deck system of UHPC pavement is expected to significantly increase the deck stiffness and then overcome the hidden dangers of fatigue cracking of steel deck structure and damage of asphalt pavement.However,the welding of bridge deck studs will inevitably cause welding fatigue of steel deck,which will bring great welding workload and bring difficulties to the replacement of bridge deck pavement in the future.Based on the National Natural Science Foundation youth fund project "Research on the mechanical behavior of UHPC strengthened concrete bridge structure considering interface fatigue damage"(52008066)undertaken by the tutor team,combined with an interface performance test and numerical analysis,this paper studies the influence of various interfaces on the mechanical performance of steel-UHPC composite bridge deck.The main research contents are as follows:(1)Direct shear test and bending test were carried out for six kinds of steel-UHPC interface,and the failure mode,strength,stress-slip curve,and interface performance of interface failure state were analyzed.Based on the fracture energy relationship of the stress slip curve,the concept of "toughness coefficient" was proposed to quantitatively evaluate the interface toughness,combined with the comparison of interface strength and interface performance of interface slip,the most effective method was put forward.The results show that the toughening effect of the quartz sand bonding interface is the best.(2)According to the toughening characteristics of steel-UHPC epoxy toughening interface,new toughening friction interface constitutive model is proposed based on the cohesion model theory.The constitutive interface model reflects the plastic stage of the interface in the trilinear shape and considers the friction effect in the tangential direction of the interface in the failure stage,so the mechanical interface behavior is more realistic.The numerical model based on the constitutive interface model is compared with the experimental results.The reliability and accuracy of the constitutive interface model are verified.(3)Taking steel UHPC composite bridge deck as an example,the interface strength,load-deflection curve,interface slip,and stress distribution characteristics of composite bridge deck under local wheel load,UHPC shrinkage,and interface defects were studied.The results show that the quartz sand bonding interface significantly improves the toughness of the steel UHPC interface,and the stud amount of the stud + quartz sand bonding interface is 50% less than that of the stud bonding interface.The mechanical properties of the steel UHPC composite bridge deck are basically unchanged.