Research On Mechanical Properties Of Lightweight Aggregate Concrete Composite Shear Connectors

Lightweight aggregate concrete has the characteristics of light weight and high strength,good fire resistance,economical and environmental protection,etc.,and has a wide range of application prospects in high-rise buildings and long-span structures.Therefore,steel-lightweight aggregate concrete composite structures emerge as the times require.The shear connector set between steel and concrete is the focus of composite structure research.Shear connectors play the role of cooperating and transmitting loads.With the development of composite structures,more and more attention is paid to the study of shear connectors.In this paper,push-out tests and finite element studies are carried out on the mechanical properties of composite shear connectors in lightweight aggregate concrete.The main research contents and conclusions are as follows:(1)The push-out test of lightweight aggregate concrete with different combined shear connector stiffness ratios and shear connector spacings was designed and carried out,and the mechanical properties,failure process and form,load-slip curves of combined shear connectors were studied.The mechanical parameters and failure modes of combined shear connections are affected by both the stud connector and the Perfobond Stripe Connector(PBL)connector.(2)Abaqus finite element software is used to establish model software to simulate and verify the push-out test,expand the finite element parameters,and discuss the influence of combined shear connector structural parameters on its ultimate bearing capacity and shear stiffness.The results show that the factors affecting the ultimate bearing capacity of lightweight aggregate concrete composite shear connections include:composite shear connector stiffness ratio,shear connector spacing,stud diameter and PBL opening diameter;The factors that determine the shear stiffness of the components include: the stiffness ratio of the combined shear connector,the diameter of the stud,the diameter of the PBL perforated plate,and the thickness of the PBL perforated plate.(3)By analyzing the influence of the structural parameters of the composite shear connector on its ultimate bearing capacity,it is suggested that the reasonable structure and layout of composite shear connectors of lightweight aggregate concrete are as follows:The stiffness ratio of the combined shear connector is close to 1,and the shear connector spacing is 50mm～150mm.(4)The stress-strain state of the lightweight aggregate concrete composite shear connector is analyzed by Abaqus finite element software,and the force transmission process of the lightweight aggregate concrete composite shear connector under load is obtained,that is,the root of the stud bears the main load in the early stage of loading,and the concrete at the root of the stud is loaded.After crushing,the main load is carried by the concrete tenon in the hole of the PBL connector.(5)According to the results of the push-out test and finite element calculation,the formula for calculating the shear capacity of the composite shear connector is obtained by fitting.