Study On Behavior Of Enforced Inner Loop Joint Of Cfst Column

The concrete-filled steel tubular column possesses advantages over either pure steel or concrete columns. As a kind of composite structure, the steel tube can provide effective confinement to the core concrete, at the same time the core concrete can prevent the steel tube form buckling. Concrete-filled steel tubular column with steel beam has been widely used in high buildings for its favorable integration performance. But the CFST column connected beam have a lot of questions, need to study deeply.Grounded on the theoretical analysis, we make use of ANSYS to conduct the finite element analysis of the enforced inner loop joint with solid modeling. We establish twelve F.E.models , for considering the behavior influence of the enforced inner loop joint by becoming width of enforced loop plane, thickness of enforced loop plane, axial compression ratio and thickness of steel tubular. We analyse the hysteretic performance of structure, stress of steel and enforced inner loop plane, the destruction mechanism of enforced inner loop joint by finite element calculation results. The analytical result is: the hysteretic curve of Enforced inner Loop Joint is full and spindle in cyclic loading. Structure have not obviously stiffness degradation and Knead shrinkage phenomenon, structure have well energy dissipation capacity. Width of enforced loop joint in (1/16~1/10)D will be the most effective. With thickness of enforced loop plane increased, the bearing capacity of joint has been improved obvious,So the thickness of enforced loop plane is important factors that affect bearing capacity of joint. When the enforced loop plane after a certain range, ductility of structures has reduce greatly, This is disadvantage to developing of the plastic hinge and resist earthquake. With concrete-filled steel tubular (CFST) column in the end of the pressure increases the bearing capacity of joint has been improved obviously, axial compression ratio in (0.4≤n≤0.8), stress in Enforced inner Loop haven't exceeded yield stress in LIMIT STATES, With the thickness of steel tubular, stiffness in the connecting place of the beam and the column of the CFST column have been improved , the bearing capacity of joint also is improved, but ductility of structures has markedly dropped, so steel ratio should control in (0.052≤α≤0.074). In cyclic loading, the area of enforced inner loop joint, the end flange of beam first achieve to yield, buckling and forming plastic hinge, then structure produce damage.