Flexural Behavior Of Web-embedded Steel-concrete Composite Beam

The web-embedded steel-concrete composite beam is a new type of composite beam.Two forms of composite beam are designed in this paper and they are web-embedded inverted T-shaped steel-concrete composite beam(WTSCB)and web-embedded Ushaped steel-concrete composite beam(WUSCB).WTSCB is a steel-concrete composite beam formed by an inverted T-shaped steel section and embedding the steel webs with grooves in the upper part into the concrete slab.WUSCB is a steel-concrete composite beam formed by U-shaped steel section which is formed by cold bending thin-walled steel plate,and embedding the U-shaped with grooves in the upper part into the concrete slab.The new composite beam has the following characteristics and advantages:(1)WTSCB omit the upper flange of the steel beam and welding procedure of stud connector for reducing steel consumption and convenient for construction.(2)WUSCB improves the design on the basis of WTSCB.The concrete slab and concrete formed in U-shaped steel form as a whole part to participate in the longitudinal shear resistance of the beam and plate interface.And also enhance the stability of U-shaped steel.WUSCB has the advantages of high flexural capacity,large structural stiffness and good ductility performance.It can form a structural system which combines WUSCB and the specialshaped concrete-filled steel tubular column structure,which is convenient for assembly construction.The experimental research,numerical analysis and design method of the flexural performance of web-embedded steel-concrete composite beam is studied in this paper.The main research work are as follows:(1)The push-out test of five embedded shear connector was studied.Their failure mode and load-slip curve of the specimen were analyzed.And the bearing capacity calculation formula of the embedded shear connector was proposed.(2)The experimental study on flexural behavior of ten WTSCB specimens and eight WUSCB specimen was studied.Their failure mode,strain distribution curve,loaddeflection curve and load-end slip curve were analyzed.The affect parameter of WTSCB is concrete slab width and form of connector.And for WUSCB,the affect parameter is Ushaped steel plate,connector spacing,concrete slab width,the diameter of longitudinal reinforcement at the bottom of the beam,stud,hooping,modified connector.(3)The finite element model of WUSCB specimens were established by ABAQUS software.The results of finite element simulation and experiment were compared and analyzed to comprehensively analyze the stress distribution of specimen.The influence of steel plate thickness,concrete slab width and the diameter of longitudinal reinforcement at the bottom of the beam on the flexural behavior of WUSCB was studied by parameter analysis of WUSCB.Basis for design method of this WUSCB were put forward.(4)Based on the experimental results and the numerical analysis results,a flexural design method for web-embedded steel-concrete composite beam were proposed.The method for WTSCB and WUSCB includes the calculation method of shear connection degree,flexural capacity and flexural stiffness.The design method is in good agreement with the test results and the numerical analysis results and the suggestions of WUSCB’s structure were put forward.