Flexural Performance Tests and Finite Element Analysis of Prefabricated Flat Beams

The prefabricated flat beam adopts prefabricated concrete slabs as the base plates and is laid on the flange plate at the bottom of the steel beam. The steel beam and concrete are combined into a whole through shear connectors and steel trusses. It has the characteristics of high stiffness， high bearing capacity， good fire resistance， convenient construction and low building height， so it has broad application prospects.In order to study the influence of different shear joints on the flexural performance of composite flat beams， a total of three composite flat beam specimens were designed， including capped stud shear joints， transverse reinforcement shear joints and non-shear joints. Flexural loading tests were carried out respectively to analyze the stress process and failure modes of the composite flat beams. The maximum mid-span deflection， ultimate bearing capacity， end slip and strain distribution in mid-span cross-section of the three specimens were compared. In order to further study the influence of different parameters on the maximum deflection and ultimate bearing capacity of the composite flat beam， the finite element numerical simulation of the composite flat beam with the capped connector was carried out by ANSYS software， and the accuracy of the model was verified by the load-deflection curve and crack location.Then， the strengths of steel and concrete， thicknesses of cast-in-place concrete slabs， reinforcement ratio， and thicknesses of steel plates were analyzed.The results showed that the composite flat beam had good integrity， flexural bearing capacity and ductility.The section strain of the flat beam during loading was basically consistent with the assumption of the flat section. The transverse shear joints at the web could effectively reduce the slip between the concrete and the section steel， and improve the flexural stiffness and bearing capacity of the composite flat beam. The finite element simulation results were in good agreement with the experimental results， which showed that the model could simulate the mechanical properties of the composite flat beam. The results of finite element parameter analysis showed： the increase of cast-in-place concrete slab thickness had the most significant effect on the flexural strength of composite flat beams， followed by the increase of concrete and steel strength. The increase of reinforcement ratio had a certain effect on the bearing capacity of the member， and could effectively improve its mechanical properties. Increasing the thickness of flange plates could effectively improve the ultimate bearing capacity of composite flat beams in the condition that the thicknesses of profile plates increased the same.