Nonlinear Finite Element Analysis Of Rectangular Steel Tube Concrete Frame Joint

In recent years, the structure of rectangular CFST (concrete filled steel tube) has appliedmore and more extensively in practical engineering, so the design methods and constructionmeasures of CFST become one of the key issues. But so far, experimental studies concerningthe shear properties of the core area of the joint are insufficient and practical calculation has notbeen proposed.The relevant existing regulations are not strictness and its content is rough,seriously affecting the application of this kind of structure in actual engineering.This paper concentrates on the finite element analysis of the existed rectangular CFSTframe joints. It studies the failure mode of joint, ultimate bearing capacity, as well as theinfluence of various parameters on the performance of the joint and analyzes a reasonable valuerange of each parameter under the circumstances of this kind of joints meet seismicrequirements by using the finite element analysis software and doing full factor analysis andunivariate analysis that can weaken the core area of rectangular CFST frame joints on the basisof the effectiveness of the verification model and the parameters including the column axialcompression ratio, the steel tube wall thickness and the column wall thickness ratio and thedepth-width aspect ratio. On account of all above analysis, this paper concludes a calculationmethod concerning the shear capacity of joint core area of the rectangular CFST.Full factor analysis shows that all joints in the core area of the are been damaged, the stressdistribution of concrete in the core area is in accordance with diagonal compression strut theory,but the beam end, the column end and the reinforcing ring board did not reach yield. The effectof the steel tube wall thickness and the column wall thickness ratio in the core area on the shearcapacity of joint core area occupies first place.With the increase of it, the shear capacity of jointcore area improves obviously. The effect of the column axial compression ratio comes second.With the increase of it, the shear capacity of joint core area drops. The depth-width aspect ratioof the core area and the type of joint don’t affect the shear capacity of joint core area.Univariate analysis shows that the column axial compression ratio should be less than0.6as well as the steel tube wall thickness and the column wall thickness ratio should be greaterthan or equal to1, so it can ensure reliable power transmission of this kind of joints.The calculation about the shear capacity of rectangular CFST frame joints is amended bysimulating the data. The formula has a clear mechanical mechanism. Meanwhile, the actual value error is less than10%. Therefore, it can be used in engineering practice for its safety andrationality.