Generating 3D interaction surfaces and assessing load-bearing capacity of rectangular reinforced concrete columns

Abstract

On designing reinforced concrete (RC) columns subjected to combined axial load and biaxial bending, checking the bearing capacity of the column after placing the reinforcement is necessary to determine the integrity of the placed reinforcement. This study developed a tool to generate the 3D interaction surfaces of rectangular RC columns subjected to biaxial flexural and axial loads using MATLAB software, according to the theory of non-linear material model. The internal moments from the software, such as ETABS, are processed to include the buckling factor according to TCVN 5574:2018, then compared with the established 3D interaction surface to assess the bearing capacity of the designed column. Two methods to check the load-bearing capacity of the columns were introduced.  Examples are illustrated in this article to apply and verify the proposed program. Compared with ETABS and CSI-Col, the errors are less than 7.2%. This program can be used for further studies, such as investigating the effect of initial parameters on the column capacity, probabilistic analysis, sensitive analysis, or generating data for machine learning.