The Mechanical Performance Reseach Of Comiposite Joints With CFST Columns With Initial Stress

With the development of the high-rise and large-scale building in recent years,concrete-filled steel tubular(CFST) structure has been widely used in engineering structuredue to higher strength and larger energy dissipation. In the period of construction,the steeltube is used as construction support and the template of pouring concrete,and the initial stresshas been existed in the tube.The initial stress in concrete-filled steel tubular connections hasbecome one of the key technical problem in the study and the spread of concrete-filled steeltube structure. At present,the mechanical performance of the basic components of theconcrete-filled steel tube(CFST) has already been researched deeply and systematicly,but theresearch for the performance of connections under the initial stress is studied not deeplyenough. According to this problem,the behavior of the connections with steel beam toconcrete-filled steel tubular column under initial stress has been studied in this paper.Themain contents are shown as follows:(1)The finite element model (FEM) of the components of concrete-filled steeltube(CFST) and the connections of steel beam to concrete-filled steel tubular column havebeen established based on ABAQUS, and the caculated results are verified with the testresults in order to verify the accuracy of the FEM.(2)The reasonable constitutive relationships of steel tube and concrete, unit model andthe solving methods have been selected. Considering the confinement effect between thetubular and concrete, the interface model and the sloving method of steel tube under the initialstress, the finite element model of the connection with concrete-filled steel tube column underthe initial stress has been established to analysis the mechanical properties under differentinitial stress coefficient and initial stress or not and the mechanism properties in differentinitial stress coefficients.(3)The in influence of parameters on the load-displacement curves of CFST conlumnsto steel beam joints have been analyzed,such as the slenderness ratio of column, axialcompression ratio,the beam to column linear stiffness ratio, and the beam to column ultimatebending moment ratio.The influence law of the concrete-filled steel tube connections underthe initial stress to the load-displacement curve have been reached, and bending-capacitymethod of joint with concrete-filled steel tube column can be obtained due to the numericalcalculation which will be the reference for engineering application.