Study On Compounding Axis Direction Compressive Stiffness Of Concrete Filled Steel Tube Columns For The Rectangle Cross-section By ANSYS Program

Concrete-filled steel tubular columns are becoming increasingly popular in high-rise buildings because of their excellent structural advantages. One of the key of mechanical problems of concrete-filled steel tube(CFT) structure is the confining effect between the steel tube and the core concrete. The key to solve the problem is to accurately describe the interfacial mechanics problems,especially to the rectangular section of CFT. After based on continuum mechanics theory, and made a small-deformation elasticity theory analysis on rectangular concrete-filled steel tube column(CFTC),the paper is numerically simulated by ANSYS program. Focus on the elastic constitutive relation, compounding elastic modulus、compounding axis direction compressive stiffness and interfacial mechanics problems to rectangular CFTC of theoretical study deeply and numerical simulation.The main conclusions of the paper as follows:(1) The CFTC is numerically simulated by ANSYS program including selecting the proper unit type, material constitutive relations and the failure criterion.(2) It can obtain the distribution function expression f1(x) and f2(y) of the CFTC of the interfacial normal force by the use of ANSYS program. The images can conveniently describe the distribution of the confining force.The images show that the distribution of the rectangular section and square section CFTC of the interfacial normal force is uneven(it shows a shape of conic similarly), the distribution of rectangular section is more uneven than the square section.There is a phenomenon of stress concentration in the corner office.The confining force is maximum in the corner and least in the midpoint.The confining effect of square section CFTC is more than the rectangular section’s.(3) The paper study the variation of compounding elastic modulus, which increased obviously with the increase of steel ratio, increased slightly with the increase of strength grade of concrete.The study also shows that the compounding elastic modulus of rectangular section CFTC is slightly smaller than the square section’s in the same steel ratio p when when a/b≤2.4,and the difference at5%. This conclusion is consistent with the literature[12].(4) The results show that the compounding elastic modulus and the ompounding axis direction compressive stiffnes of CFTC is higher than the conversion elastic modulus and the conversion axial stiffness without considering the confining effect,the compounding elastic modulus is higher than the conversion elastic modulus and the ompounding axis direction compressive stiffnes is higher than the conversion axial stiffness in the range of calculating.