Research On Behavior Of Concrete-filled Steel Tubular Composite Frame To Resist Progressive Collapse

The American Society of Civil Engineers (ASCE) standard ASCE7-05definesprogressive collapse as the spread of an initial local failure from element to element thateventually results in the collapse of an entire structure or a disproportionately large part of it.There are two reasons for causing the progressive collapse event, including human factors andnatural factors. Usually, structure collapse will result in serious personal injury and propertydamage. With the number of progressive collapse events increases in recent years, the studyon progressive collapse has become a hot issue. With the wider use of concrete-filled steeltubular (CFST) structures in the field of architecture, CFST frame structure was used in somecomplex structures such as high rise and super high rise buildings, but it still lack of researchon progressive collapse resistance of CFST frame structure. In this paper, non-linear dynamicanalysis is carried out for a typical12stories CFST frame structure based on the alternate pathmethod. The main achievements can be summarized as follows:(1) Reasonable constitutive model and failure criteria were selected and used, and a planarcomposite frame model with CFST columns was built in ABAQUS. The column removalconditions include the side column removal, the middle column removal, two adjacent sidecolumns removal, and two adjacent middle columns removal. The joint displacement variationtendencies above the removing column and other components internal force around the removedcolumn were investigated.(2) A FEA model of spatial composite frame with CFST columns was built in ABAQUS,removing the longitudinal middle CFST column, transverse middle CFST column, cornercolumn, and internal column at the ground story, respectively. Nonlinear dynamic analysis wascarried out for the sudden loss of columns for different conditions of column removal. The jointdisplacement variation tendencies above the removing column and other components internalforce around the removed column were investigated, and comparative analysis with plane framewas developed.(3) Multi-scale finite element modeling of planar composite frame with CFST columnswas built. The analysis on progressive collapse based on alternate path method was performed,and the stress distribution of the local micro model was also analyzed. The measures forpreventing the composite frame structure collapse were presented based on the evaluation forthe ability of progressive collapse resistance. The analysis results indicated that the spatialcomposite frame with CFST columns has better ability on progressive collapse resistance thanthe plane frame. The composite slabs can greatly improve the progressive collapse resistance of frame structures. In addition, the load was transferred to the adjacent columns under aproximity principle after removing the columns.