Study On Shear Performance Between Composite Floors And Cold-formed Thin-walled Steel

In the cold-formed thin-walled steel composite floor system,the connection surface's shear bearing capacity between the floor and the composite floor pays an important part in the composite floor's shear capacity.And when the connectors that connect the floor beams and composite floors are in a relatively complex boundary condition(such as pouring concrete and adding connector on the self tapping screws of the connecting press plate and the building cover beam),the results of the shear test of the single connector are no longer applicable and the domestic standard lacks the calculation standard for the shear strength of composite floor under complex boundary conditions.Therefore,it is necessary to systematically study the shear performance between cold-formed thin-walled C steel and composite floors and the main contents of research are as follows:(1)In order to obtain some indexs of composite floor such as hysteresis curve,skeleton curves,strength degradation curves,stiffness degradation curves and energy dissipation capacity,five cold-formed thin-walled C steel-composite floors were tested under the reversed cyclic load,the loading direction paralleled to the length direction of composite floor.The results shows that the main reason for the decrease of bearing capacity of specimens is the separation of profiled steel sheets from concrete,and the self tapping screws are inclined or pulled out.The initial stiffness,ultimate bearing capacity,integrity of the composite floor and energy dissipation capacity are improved by adding the shear connector.(2)By using the finite element software ABAQUS for the finite element models of cold-formed thin-walled C steel,the FE analysis results were compared with the experimental results so as to determine the simplified form,boundary condition and connection mode in finite element software.(3)Establishing the finite element models to learn some parameter such as screw spacing,connection stiffness,CFTS web with openings and steel yield strength.The results show that the initial stiffness,ultimate bearing capacity and energy dissipation capacity of the composite floor can be improved by reducing the spacing of the self tapping screws and increasing the connection stiffness between the components.The opening of the C type steel beam and the increase of the yield strength of the steel are not obvious to the initial shear stiffness of the composite floor interface.