Strength of Short Centrally Loaded Concrete-Filled Steel Tubular Columns

The purpose of the research is the development of a theoretical basis for evaluating the strength resistance of short concrete-filled steel tubular column (CSТC). A solution of this issue is accompanied by certain difficulties due to the necessity to consider complicated stressed state of materials. Existing formulas to calculate concrete core strength have been reviewed. The formulas used to determine the lateral pressure and strength of a volumetrically loaded concrete core and steel holder stress in a limit state of a column have been received theoretically for the first time. A procedure for deformation calculation of CSTC strength is proposed. The obtained formulas and calculation procedure have been used when developing a computer program for the automated calculation of such structures. The correctness of the calculations carried out with the use of the developed program has been validated through correlation of the experimental values of the destructive loads with the estimated data. A coefficient of error vector variation calculated based on this correlation amounted to 0.04 evidencing high accuracy of the calculations. The new formulas recommended by this article to calculate volumetrically loaded concrete core strength, axial direction strain in the concrete core, axial direction stress in the steel holder, steel holder lateral pressure on the concrete core, and the scale factor coefficient allow to determine correct strength of centrally loaded CSТC.