| The influence of concrete creep on the behavior with initial concrete imperfection filled steel tubular columns subjected to sustained load were investigated in this paper. The system research of void imperfection CFST under long-term load, the main achievements can be summarized as follows:(1)8short columns test on the behavior of concrete-filled steel tubular columns under long-term sustained loads, in additional to provide further12short columns test on the static Load-bearing Capacity of the composite columns, were performed in this paper.(2) The analytic model of Void Imperfection CFST columns subjected under sustained loading were analyzed by finite element method. And load-deformation relationship curves of Void Imperfection CFST columns under sustained loading were calculated. The predicted load versus deformation relationship curves are in good agreement with those of tests.(3) The analytic model of Void Imperfection of CFST axial and eccentric columns under long-term sustained loading with the influence of void imperfection types and gap rations to analyze stress distributions of steel and concrete, interactions between steel and concrete, and failure modes of CFST columns under sustained loading were analyzed by finite element method.(4) Based on finite element model, the influences of sustained time, sustained load level, nominal steel ratio, and strength of the materials, imperfection type, gap ration and ultimate bearing capacity of the CFST columns with long-term sustained loading effects were analyzed. Formulas to calculate the ultimate bearing capacity of the Void Imperfection CFST columns with long-term sustained loading effects were proposed. |
