Experimental Study On The Shear Behavior Of The Prefabricated Composite Beam High Strength Bolt Connector

High strength bolt connection has the characteristic of the tight connection,excellence in loading,anti-fatigue,strong disassemble,easy installation and so on.In China,the research on the application of high strength bolts as shear connectors in steel-concrete composite beam is a little,High strength bolt can be the connection of the prefabricated steel-concrete composite beam and the connection performance of shear connectors is the key to ensure the overall work of the assembled composite beam,so it is very important to study the behavior of the high strength bolt connector.This paper proposes a prefabricated steel-concrete composite beam the connector of that is high strength bolt in order to improve the assembly of steel-concrete composite slab and composite bridge structure to adapt for the development needs of assembled composite structure.A total of 22 specimens were designed to conduct push-out test with the test parameters of the aperture ratio(the ratio of the reserved aperture and bolt diameter),the bolt diameter,and the pore forming mode to study the shear performance of prefabricated high strength bolt shear connectors.By the test,the failure mode,shear capacity and load-slip cuve of cast-in-plate push-out specimen and prefabricated assembling specimen were got,and the mechanical properties of the shear connector,the bolt bearing capacity ratio(the ratio of the bolt shear force and the standard value of the bolt shear force),the average shear stress slip curve,the normalized fitting curve,the ductility and the deformation capacity are analysed.The results show that all the specimens were the shear failure of bolt,and the fracture occurs at the interface of concrete slab and steel beam;the shear strength of the bolt can be improved by selecting the appropriate aperture ratio;the ductility of cast-in-plate specimen is slightly better than that of fabricated specimen,but the shear bearing capacity is equal,and when the aperture ratio is 5.8,the shear strength of the fabricated specimen is better than that of the cast-in-place specimen;the load slip curve is basically linear when the load of high-strength bolt is less than 0.35 times peak load;the shear connector with high strength bolt in prefabricated steel-concrete composite beam is reliable.The experimental and theoretical analysis of the paper shows the prefabricated steel-concrete composite beam with the high strength bolt as the connector presented in this paper has the feasibility to be applied in practice,and the structure form is simple and the construction efficiency is high,reasonable design can meet the requirements of the current specification;the smaller the diameter of the high strength bolt,the larger the aperture ratio,the weaker the constraint degree(the different pore forming method),the better the shear behavior.