Behavior Of Concrete-Filled Steel Tubular Composite Frame After Exposure To Oerall Stage Of Fire

Concrete Filled Steel Tube (CFST) structures have been widely used inconstruction projects due to high bearing capacity, excellent seismic performance andrefractory performance compared with steel structures and reinforced concretestructures. Building fire accidents have been serious threatened to human life andproperty. in recent years. It is necessary to research the performance of CFST columnsto composite beam frames subjected to heating and cooling fire damage for evaluation,strengthening and repairing the structure after exposure to overall stage of fire. Themain research work includes:(1). Based on the determination of concrete and steel thermal model, thetemperature field model of CFST columns to composite beam frames under heatingand cooling phases were developed due to accurate boundary conditions and meshing.The temperature distributions of columns and composite beam were studied based onfinite element model (FEM).(2). Determinations of the reasonable material properties of concrete and steel inambient, heating, cooling and post-fire phases, The mechanical FEM of CFSTcolumns to composite beam frames were developed in order to analyze the entireprocess under the combined loads and fire including heating and cooling phases. Theresults were compared with ambient and not take into account for cooling phase(natural cooling).(3). Influence of parameters, such as the steel ratio of column, load ratio ofcolumn, heating time ratio, the depth of fire protection, the concrete strength ofcolumn, the strength of steel tube and slenderness ratio were analyzed based on thecurve of P-Δ.