Behavior Of Concrete Filled Tubular Members With Inner Profiled Steel Under Initial Stresses On Steel Tubes As Well As Long-term Sustained Loads

In this paper, the research on behavior of Concrete Filled Tubular columns with inner profiled steel subjected to axial load and eccentrical load under initial Stresses on steel tubes and long-term sustained loading was carried out by the finite element software ABAQUS. The main contents are as follows:(1) Concrete Filled Steel Tubes with preload on steel tubes were firstly caculated, which result were in good agreement with test result, based on this, the analytic model of Concrete Filled Tubular columns with inner profiled steel subjected to axial load and eccentrial load behavior under initial stress on steel tube were established. The load versus deformation of Concrete Filled Tubular columns with inner profiled steel with different initial stress ratio was calculated, the working mechanism of composite columns under initial stress were studied. The influence rule of initial stress ratio, slenderness ratio, load eccentric ratio, concrete cube strength, etc on strength index kp were analysed systematically. The result shows that initial stresses on the influence of bias columns’ s ultimate bearing capacity could not be ignored.(2) Deformation versus time and Load versus deformation relationship curves of CFST columns subjected to axial load considering the influence of sustained load were calculated, which result were in good agreement with test result, based on this, the analytic model of Concrete Filled Tubular columns with inner profiled steel subjected to axial load and eccentrial load behavior under sustained loading were established. The long-term deformation and stresses distribution of composite columns were analysed. The load versus deformation relationship curves were calculated. The working mechanism of Concrete Filled Tubular columns with inner profiled steel subjected to axial load and eccentrial load behavior under sustained loading were studied detailedly. The influence rule of long-term sustained load level, slenderness ratio, load eccentric ratio, concrete cube strength, etc on strength index kcr were analysed systematically. The result shows that sustained loading on the influence of bias columns’ s ultimate bearing capacity could not be ignored.(3) Based on the contains of(1) and(2), the analytic model of Concrete Filled Tubular columns with inner profiled steel subjected to axial load and eccentrial load behavior under initial stress and sustained loading were established. The influence of initial stress on steel tube on static behaviors of columns at sustained loading period were analyses. The load versus deformation relationship curves of composite columns are calculated, which curves were compared with the curves considering not initial stress and sustained loading and considering only sustained loading. The influence rule of initial stress ratio, final creep coefficient long-term sustained load level, slenderness ratio, load eccentric ratio, concrete cube strength, etc on strength index kpcr were analysed systematically. The result shows that initial stresses on steel tube and sustained loading on the influence of bias columns’ s ultimate bearing capacity could not be ignored.