Study On Mechanical Properties Of Prefabricated Slab Connection Joints And Composite Beam

Prefabricated buildings have has been widely concerned because of its high production efficiency,green energy saving and environmental protection advantages..The floor system is an important part of the building structure system.The assembly method of the prefabricated floor is directly related to the integrity of the building,and the connection of the plate joints needs to be paid more attention.In view of the existing structural problems,this paper proposed two structural forms of beam-slab splicing joints,and carried out experiments,numerical modeling analysis,and theoretical calculations,in order to provide an effective connection for slab joints in prefabricated buildings.The mainly task and conclusion as follows:(1).Classifying the beam-slab splicing joints according to the construction process,This paper designed a new type of wet joints and dry joints,in order to reveal the deformation characteristics,shear resistance and failure modes of the new joints under shear conditions.15 specimens were designed and processed,and push-off tests of shear connectors were conducted.The test results show that the specimens present two different failure modes.In the wet connection specimens,the failure modes of the specimens that were poured by ordinary concrete are concrete crushing,with low load-bearing capacity and good ductility;The failure modes of the specimens that were poured by UHPC and dry-connected specimens are both shear failure of the shear connectors.There is no obvious crack on the surface of the concrete,and it makes a louder noise when it fails.It has high load-bearing capacity,poor ductility,and obvious brittle failure.(2).The effect of the diameter of the shear connector,the length of the stud,and the strength of post-pouring concrete on the mechanical properties of the joints was studied.Among them,the diameter of the shear connector has the greatest influence,the length of the stud and the strength of post-pouring concrete can also improve the shear resistance.At last,the suggested design formula of the bearing capacity for these two types of joint is presented,and the theoretical calculations are in good agreement with the experimental values.(3).In order to reveal the deformation characteristics,flexural bearing capacity and failure mode of the composite beams under bending,three composite beam specimens were designed and the bending test research was carried out.The test results show that the wet-connected composite beams belong to a flexural failure mode and have higher flexural bearing capacity.The dry-connected composite beams showed shear failure mode and had low bearing capacity,but the ductility is higher than that of the wet-connected composite beams.(4).In order to study the factors such as the strength of post-poured concrete and steel beams on the flexural performance of composite beams,a finite element model of the flexural test was established and compared with the test results to verify the accuracy of the finite element model.By further parameter analysis,a calculation method for the flexural bearing capacity and flexural rigidity of the composite beam under the new type of plate joint connection node form was proposed.