Static Behavior Study On The Axial Pressure Perfomance Of Bar-reinforced Concrete-filled Circular Steel Tubular Short Column After Exposure To Fire

Bar-reinforced concrete-filled steel tubular column is filling the longitudinal steel bars in concrete filled steel tubular column, forming a new type of composite structure. The structure is simple, but exposure to fire, the intermal steel bars heat up slowly and their strength can loss smaller with the function of concrete for improving the fire resistance; After exposure to fire, the strength of the steel can recover, mechanical properties can be more improved than exposure to normal temperature, and the integrity of the structure is better than exposure to fire, not only for the structure reinforcement provides a safer working environment, also can reduce the workload and maintenance cost. So experimental study and finite element analysis are carried out for bar-reinforced concrete-filled steel tubular short column after exposure to fire, the main work is as follows:(1) In this paper, twelve columns after exposure to fire and six columns subjected to normal temperature are investigated experimentally in residual strength of bar-reinforced concrete-filled circular steel tubular short columns, and two columns are investigated experimentally in temperature. Research shows that the failure mode of all specimen is shear failure, shear angle is about 45 ° with normal temperature, and shear angle is about 60 ° after exposure to fire; the remaining time of fire is the main factor influencing the residual strength, with the increasing of fire warming time, the residual strength will be reduced; the reinforcement ratio is not very important.(2) Finite element analysis model was established based on finite element software ABAQUS, and verified the experiment in the paper and collected relevant test data, the results are in good agreement indicates that data, the model is correct.(3) Studying the influence law of the residual strength such as fire warming time, section size, strength of materials and so on in greater detail; Then a calculation formula of residual bearing capacity is regressed, and it is convenient to be used in engineering practice. Results show that the fire warming time and section size are the main factors for affecting the residual strength.