Analysis of Ultimate Bearing Capacity of Concrete-filled Steel Tubular Axial Compression Short Columns

According to the bearing capacity of concrete-filled steel tubular axial compression short columns,based on the twin-shear unified strength theory,the calculation formula of bearing capacity of concrete-filled steel tubular members subjected to axial compressive short columns was derived.In this formula,the intermediate principal stress and the reciprocity force between strain-constrained concrete cylinders and steel tube were considered sufficiently.The restrain action of concrete and the circumferential stretching of the steel tube both produced by the reciprocity force were taken into account,these made the compressive strength of concrete enhanced,and made the compressive strength of the steel tube reduced.The values for lateral pressure coefficients and for material strength parameters were analyzed and discussed.A comparison between the theoretical results and the experimental data in the literature was achieved.The results indicate that the twin-shear unified strength theory is versatile in the theoretical analysis of concrete-filled steel tube and considering the effect of the reciprocity force is very necessary.The reliable theoretical foundation can be provided for the optimum design of concrete-filled steel tube.