Finite Element Analysis On Axial Compression And Seismic Behaviors Of Multibarrel Tube-Confined Concrete

In the past several decades, all kinds of concrete-filled steel tubes have obtained widespread application because of their excellent mechanical properties. The application such as high-rise buildings and bridges has achieved satisfactory economic benefits. Especially, the concrete-filled double skin steel tubes(CFDST) have many new characteristics and broad application prospects, however the phenomenon of local buckling of steel pipe always can be found when the columns fail. In order to improve its ability of resisting the local buckling, a longitudinal rib is welded between the internal and external steel tube, which is a new type of multibarrel tube-confined concrete. However there are less study on this tube can be found. So it is necessary to preliminarily study the axial compression performance and seismic behavior of this tube by using the finite element analysis software ABAQUS. The research contents and results include:1. Based on selecting constitutive model and element type of steel and concrete, the analysis model is established which is verified by the experiment to analysis the axial compression performance. The results show that compared with concrete-filled double skin steel tubes, the deformation characteristic, carrying capacity and ductility of multibarrel tubeconfined concrete is improved obviously.2. The effect of the hollow ratio, steel strength, concrete strength, steel pipe size on the axial compression carrying capacity is analyzed, and the formula of axial compression carrying capacity is put forward. The formula match with the results of finite element analysis and experimental well.3. The finite element model under the action of monotonic horizontal load is established to study the mechanical performance. The influences of axial load level, hollow ratio, slenderness ratio, strength of steel and concrete on the load-displacement relationship curve is analyzed systematically which set up the foundation for further putting forward calculation model of skeleton curve.4. The finite element model under the action of lateral low reversed cyclic load is established to study the hysteretic performance. The results show that the failure mode, deformation capacity, stiffness degradation characteristics and energy dissipation capacity of multibarrel tube-confined concrete are better than the concrete-filled double skin steel tubes.