Study On Load Bearing Capacity Of Crisscross Section Column Composed Of Concrete-filled Square Steel Tubes

Recently certain progress has been made on the study of concrete-filled square steel tubular (CFST). Based on a quantity of theoretical research and engineering practice, technical specifications have been implemented for designers in many districts. However, little research data has been attained on the study of special-shaped column of CFST. A new special-shaped column type——the crisscross section column composed of CFST is put forward in this paper. Advanced research has been done on the mechanical performance of the new type column from aspect of theory, analysis by finite element method and experiment.Analysis has been done on the superposition theory for the calculation method of column of CFST. According to the theoretical analysis and supersonic detection data of concrete-filled steel tubular, application basis for calculating CFST by superposition theory is advanced. Base on the analysis of superposition theory, a new calculation theory of the column of CFST is brought forward and the calculation formula is derived. Under the deformation compatibility condition, the calculation formula for distribution coefficient of axial compression is derived. The calculation formula for the conversion slenderness ratio of the crisscross section column composed of CFST and the increasing coefficient of the stability of the steel tube is determined.The numerical simulation analysis of the model for the crisscross section column composed of CFST is carried out by the finite element software of ANSYS. Through comparison of the results by analysis of ANSYS and theoretical calculation, the feasibility of superposition theory, by which the crisscross section column composed of CFST can be calculated, is verified preliminarily.On the base of theory calculation, two crisscross section columns composed of CFST are designed, one is long column specimen, and the other is short one. Monotone static axial compression experiments are made for the crisscross section column composed of CFST. Test of material and supersonic detection are finished for the two specimens before axial compression experiment. Though the test, the mechanical performance of the specimen is gained. Also the mode of bucking is presented. Through comparison of the results by theoretical calculation and the experiment, it is found that the result by two methods consist with each other well.