Finite Element Analysis On High-strength Concrete-filled Square Steel Tube Slender Columns With Inner CFRP Circular Tube Under Axial Load

Concrete filled square steel tube has applied foreground in the engineering field along with the maturation of the theoretical research of the concrete filled square steel tube. Compared with the round concrete-filled steel tube, the square concrete-filled steel tube has no better than it in bearing capacity, but because of its own with a bending cross-section Rigidity, the node structure simple and easy decoration, etc., which in recent decades to each other at home and abroad to carry out a large number of concrete-filled steel tube studies, the actual engineering is also on the rise.High-strength concrete filled square steel tube column with inner CFRP circular tube is a new kind of composite column on the basic of CFST. It is consist of an outer square steel tube and carbon fiber-reinforced polymer (CFRP), with the space filled with high-strength concrete. Its biggest characteristic is reducing the stress focus on the corner of square steel tube by CFRP tube, and increase the bearing capacity and ductility of specimens.Load versus deformation relationship curves of high-strength concrete filled square steel tube long column and high-strength concrete filled square steel tube long column with inner CFRP circular tube subjected to axial loading were analyzed by finite element method. Comparisons between the predicted results and tested ones were carried out, and good agreements were achieved. Since verified by tested results, it demonstrated that the numerical method is reliable in predicting the load versus deformation relationships.The finite element analysis on high-strength concrete filled square steel tube middle-long column with inner CFRP circular tube and high-strength concrete filled square steel tube middle-long column have been applied by ABAQUS. The slenderness ratio, steel ratio, CFRP layers and other parameters have been analyzed on the mechanical properties of specimens. The changes of dynamic stress of core concrete, laminated concrete, steel square tube and CFRP tube in the loading process also have been simultaneously considered. It can be seen that CFRP constraint on the core concrete is not obvious before middle-long conlumns arriving at ultimate strength, while CFRP constraint on the core concrete has an obvious increase after middle-long conlumns arriving at ultimate strength. Content of CFRP has significant effect on mechanical performance of high-strength concrete filled square steel tube middle-long column with inner CFRP stub column after load-displacement curves passed the highest point. Decaying of bearing capacity after ultimate value will be lessened and prevented. The breaking bearing capacity (when CFRP start to break) of the stub column under axial loads will grow up. The ductility of specimens has been greatly increased in the late of loading process.The finite element analysis on high-strength concrete filled square steel tube long columnwith inner CFRP circular tube have been applied by ABAQUS. The finite results have a good agreements with tested results. The working mechanism of long conlumn also has been studied in-depth. It can be abtained that CFRP tube not only buite confining constraint on the core concrete, delayed the yield time of component, but also greatly improve the ductility and failed strength of the specimen. On this basis, the slenderness ratio, steel ratio, CFRP layers and other parameters have been analyzed on the mechanical properties of high-strength concrete filled square steel tube long column with inner CFRP circular tube.