Fire Resistance Of Concrete Filled SHS Columns With Effect Of Adjacent Wall

Modern buildings develop towards super high-rise, long span and functional buildings, because of the rapid increase of population. The population intensity and possibility of fire is high in high-rise and super high-rise buildings. It is difficult to evacuate people and put out of fire once it happens. Therefore fire may cause huge economic losses and casualties. Concrete filled steel tubular (CFST) columns have been widely adopted in high-rise and super-high rise buildings, due to the high load bearing capacity, good seismic performance, easy construction and high fire resistance. However, most of previous studies assume that columns are subjected to fire uniformly. Current design standards also adopt this hypothesis. In real structures, the fire boundary condition of columns varies because of the adjacent walls, which means those members may be subjected to non-uniform fire. And then fire performance of those members may be different from the uniform exposure condition. Therefore this paper focuses on the effect of adjacent walls on the fire resistance of concrete filled square hollow section (SHS) columns. The main three parts are as following:(1) Thermal analysis of concrete-filled SHS columns with the effect of adjacent walls.A finite element (FE) model of concrete filled SHS columns was developed using the program ABAQUS, to simulate the thermal distributions, after determining the thermal properties of steel, concrete and walls. The FE model was validated with test results. The effect of adjacent walls on the thermal field of concrete-filled SHS columns was discussed. Differences of the thermal distributions to those in uniform fire were analysed, which provides the basis for the latter analysis.(2) Stress analysis of concrete-field SHS columns with the effect of adjacent walls.Based on previous studies, stress-strain relationship models were determined for the steel and concrete. A FE model of concrete-field SHS columns was developed using the program ABAQUS. And the FE model was validated with related experimental results. After that, the mechanism and fire resistance of concrete-field SHS columns with effect of adjacent walls were analysed.(3) Parametric studies of concrete-field SHS columns with the effect of adjacent walls and design methodsParametric studies was conducted to identify the influences of the cross-sectional dimension, the slenderness ratio, the area ratio of steel tube to concrete, the load ratio, the concrete compressive e strength and the steel yield strength on the fire resistance of concrete-field SHS columns with the effect of adjacent walls. Based on the parametric study results, design methods were proposed for predicting fire resistance of concrete-field SHS columns with the effect of adjacent walls.