| The steel-concrete composite beam can make full use of the material performance advantages of steel and concrete,and has the advantages of light weight and high bearing capacity.Combining the construction methods of factory prefabrication and on-site assembly can significantly improve the construction quality and construction speed of composite beams,and save construction costs.Shear connectors are the key components to ensure that the steel main girder and the precast concrete slabs are cooperatively stressed and become the key components of the composite structure,and their shear performance directly determines the combined efficiency of the structure.Aiming at the stress and construction requirements of the prefabricated steel-concrete composite beam anti-shear connector,this paper proposes a new type of bearing-shear connector,and uses a combination of push-out tests and nonlinear finite element analysis.The shear capacity,stiffness,load-slip curve of the connector are systematically studied,and the main research contents and conclusions are as follows:A total of 15 push-out test specimens in 5 groups of bearing-shear connectors were completed,and the crack distribution law,failure form,shear capacity,shear stiffness and load-slip law of B-S connectors under different geometrical parameters were obtained.The push-out results show that the shear capacity and shear stiffness of the B-S connector are both high.The shear capacity of a single B-S connector is equivalent to that of nine head-stud connectors with a diameter of 22 mm,and its characteristic slip value is between 17.2 mm～35.0mm,which is much larger than the 6mm requirement in EC4.The B-S connector is a typical ductile connector;A non-linear finite element model of the compression-shear type connector was established to simulate the whole process of the connector under load from shearing to failure,and the load-slip curve,failure mode and shear capacity were obtained.Based on the small differences between the numerical simulation and the test results,the reliability of the finite element model is verified.The verified finite element model is used to analyze the influence of the structure and height of the bearing plate,the thickness and strength of the shear plate,the strength of concrete and the steel bars on the shear performance of the B-S connector.The results show that the structural form of the bearing plate has little effect on the shear capacity of the B-S connector,and the height of the bearing plate has little effect on the shear capacity and stiffness of the B-S connector.The shear capacity of connectors increases linearly with the increase of the thickness of shear plate,ultimate tensile strength of shear plate and concrete strength.Shear plate thickness and concrete strength have a greater influence on the shear stiffness of B-S connectors.With the increase in the diameter of steel bars,the shear capacity of the connector increases less,and stiffness of the B-S connector remains basically unchanged.Based on the results of the push-out tests and the finite element parametric analysis,it is found that the failure mode of the compression-shear type connector is similar to that of the head-stud connector.With reference to the shear calculation theory of the head-stud connector,the shear capacity of the B-S connector is obtained.The calculation formulas of capacity,shear stiffness and load-slip curve can be seen from the co MParison of theoretical calculation results and experimental or finite element results.The theoretical formula proposed in this paper has higher calculation accuracy. |
PDF Full Text Request