Study On Mechanical Properties Of The Hybrid Bonding Shear Connection Of Steel-concrete Composite Beams

Most of the existing composite structures use studs as shear connectors.There are still some problems that need to be improved for this type of connectors: the stud connectors embedded in the concrete slab will induce stress concentration,causing the concrete slab to crack,reducing the service life of the composite beam;the stud is connected with the steel beam through welding,which is easy to produce defects;under the fatigue load,the durability of the composite structure will be reduced.In order to avoid these shortcomings of stud connectors,this paper carries out the experimental research on the hybrid bonding shear connection by using the stud shear connector and the epoxy mortar shear adhesive layer at the same time.The specific research contents are as follows:(1)Experimental study on mechanical properties of epoxy mortar and bonding interface.The tensile strength of the epoxy mortar layer,the bond strength of the interface under different compressive strength of concrete,the failure mode of the interface,the load slip relationship of the interface,and the bond stress distribution of the interface are studied.In this paper,18 tensile strength specimens of epoxy mortar and two groups of 7 specimens were designed to analyze the mechanical properties of epoxy mortar.(2)Study on the interface mechanical properties of single pin push-out specimen with composite adhesive anchorage connection.The interface failure mode,the load slip relationship,the stress distribution of section steel and the bond stress distribution of epoxy mortar layer are studied.The results are compared with those of only stud connection specimens and only epoxy mortar layer bonding specimens.Seven test pieces were designed according to the test purpose.(3)The mechanical properties of push-out specimens with group nail composite bond anchorage were tested.11 specimens with two different parameters were designed.At the same time,the interface failure mode,the load slip relationship,the stress distribution of section steel,the bond stress distribution of epoxy mortar interface and the stud strain were analyzed.The results are compared with those ofonly stud connection specimens and only epoxy mortar layer bonding specimens.