Study on the mechanical properties of hybrid bonding shear connections with shear studs and epoxy mortar layer

This paper designed a new type of hybrid bonding (HB) shear connections consisting of both epoxy mortar layer and shear studs, to avoid the shortcomings such as stress concentrations and welding defects accompanied with the use of the traditional stud connectors in composite structures. In order to study the mechanical behavior of the hybrid connections in a systematic fashion, this work carried out several experimental tests, including measurement under static loads and push-out tests on specimens with epoxy-mortar shear connections and hybrid connections containing single stud and group studs, respectively. During those experiments, several parameters that affected the mechanical behavior of the connectors were investigated, such as the failure mode, interfacial slip, as well as the load-displacement relation and bonding capacity, etc. It was demonstrated that the shear capacity of the specimens with hybrid shear connection was generally higher than that with pure shear studs. What’s more, it was found that the failure/debonding could appear at interfaces between adhesive layer and steel girders/concrete structures. The aforementioned experiments illustrated that the epoxy mortar layers possessed excellent shear capacity and effectively avoided the stress concentrations by the shear studs. Regarding the post-debonding process, hybrid connections exhibited similar mechanical behavior as the shear studs within the epoxy mortar layer. In general, it is concluded that the proposed hybrid connection is superior and is recommended for the shear connection of composite structures relative to the traditional stud connectors.