Cyclic Performance Of Concrete-Filled Steel Tubular Columns With Initial Concrete Imperfection

In this paper, based on the experimental study and theoretical analysis, the hysteretic behaviour of concrete-filled steel tubular (CFST) specimens with initial imperfection was carried out deeply. The main works can be summarized as follows:(1) The research status of CFST columns with initial imperfection and the seismic performance of CFST specimens were systematically reviewed.(2) Including 18 CFST specimens with initial imperfection specimens and 6 counterparts, 24 CFST beam-columns were tested under cyclic loads. The experimental parameters include gap ratio, axial load ratio and the wall thickness of steel tube. The influences of three parameters on strength, stiffness, energy dissipation and ductility were investigated.(3) After determining the stress-strain model of steel and core concrete under cyclic loads, numerical modelling was conducted using finite element (FE) analysis software ABAQUS. The existing test data were used to verify the accuracy and reliability of this FE model.(4) Based on the FE model, effects of gap ratio, concrete strength, steel yielding strength, steel ratio, slenderness ratio and axial load ratio on the P-â–³ curve of CFST members with initial imperfection were studied.(5) Using the FE model, the whole process of P-â–³ relationships of CFST beam-columns with initial imperfections were analyzed. The stress distributions of the steel tube and core concrete and the interaction between steel tube and core concrete were investigated. The influences of initial imperfections on the working mechanism of CFST beam-columns were studied and The study may provide reference to practical construction as well.