Research On The Combined Force Performance Of Cemented And Welded Nail Group Connectors

Steel-concrete composite girder bridges are widely used in bridge construction because of their good mechanical properties and remarkable economic benefits.Typically,steel-concrete composite girder Bridges are made up of steel girders and concrete combined together through metal shear connectors,the most common of which are stud shear keys.With the increase of service time of steel-concrete composite girder bridge,under the continuous action of vehicle load,the problems of stud stress concentration,welding quality,and the decrease of service life and durability of composite girder under material fatigue load have been commonly seen in bridge engineering.At present,prefabricated structure has been popularized and applied in bridge construction.For example,after the deck of composite girder bridge is changed from cast-in-place to prefabricated,epoxy mortar is often used in construction to prevent the bottom of prefabricated bridge deck from emptiness and prevent water vapor infiltration of the joint surface to ensure the safety and improve the durability of prefabricated composite girder.For this reason,another type of connection between concrete bridge deck and steel girder is put forward,that is,a mixed shear joint composed of studs and cementing layers.Based on cementing and fitting combination study of mechanical performance of welding group,the concrete research contents and results are as follows:(1)By conducting cementation welding group of mixed shear connectors launch test and the numerical simulation analysis is given by finite element software ABAQUS cementation hybrid welding group to the stress distribution and mechanical characteristics of shear connectors,research shows that:in cementing welding group of mixture of shear connectors,epoxy mortar cementing layer before the stud stress;The distribution law of bond stress at the interface of the cemented layer is complex,mainly showing the nonlinear distribution of "W" and "U".The stress on the steel beam and the stress of the weld are concentrated around the root and the root of the weld respectively.(2)By conducting cementation welding group of shear connectors to launch in the mixture,it is concluded that different welding screw diameter,distance between welding and welding screw height on cementing welding group of mixed effect the performance of shear connector to connect,the results of the study concluded that within a certain range,increasing the stud diameter is the effective way to increase resistance of the cementation welding group of the shear strength and shear stiffness of shear connector.(3)By using finite element software ABAQUS is used to numerically simulate analysis cementation layer,whether there is a cement layer,different material and different thickness of cementation filling holes cementation welding group of mixed effect the performance of shear connector to connect,cementation layer thickness was put forward for cemented welding group of mixed shear connectors of shear bearing capacity formula,the influence of the study concluded that:by setting the cementation layer and the way to increase cementation layer thickness can effectively enhance the cementation hybrid welding group limited bearing capacity of shear connectors;When the hole filling material is epoxy mortar,the ultimate bearing capacity of the mixed shear joints of cement-based grouting material is larger than that of the specimen with epoxy mortar.(4)Based on the introduction test and finite element numerical simulation analysis of the bonded stud group mixed shear connectors,the calculation formula of the influence of shear bearing capacity of the bonded stud group mixed shear connectors in accordance with the experimental study in this paper is proposed,which provides a reference for the design and calculation of the bonded stud group mixed shear connectors in the future.