A Simplified Method for Determining the Bearing Capacity of Eccentrically Compressed Rectangular CFST Columns with Eccentricities in Two Planes

Rectangular concrete-filled steel tubular (CFST) columns are among the most promising types of load-bearing structures. Compared to circular CFST columns, they are more effective in resisting eccentric compression. Existing analytical calculation methods enable the determination of the bearing capacity of eccentrically compressed CFST columns in the presence of axial force eccentricity in only one plane. The purpose of this work is to develop an analytical method for calculating the bearing capacity of eccentrically compressed CFST columns in the presence of bending moments in two planes.

The proposed model is based on the theory of limit equilibrium. Four main variants of the neutral line location in the cross-section at the moment of destruction are identified. For each variant, resolving equations are obtained that allow for determining the ultimate load, which can be solved using the publicly available Microsoft Excel Online software.

The developed method was tested on experimental data for 38 samples. The correlation coefficient between the experimental and calculated values was 0.979. There is also good agreement between the results of analytical calculations and the results of finite element modeling.

The deviation of the experimental ultimate load values from the calculated ones can be attributed to the scatter of experimental data and the local loss of stability effects on the pipe wall.

Engineers can use the proposed method for a preliminary assessment of the bearing capacity for eccentrically compressed CFST columns at the stage of selecting design solutions.