Study on axial compression capacity of multi-spiral hoops confined concrete columns

Axial bearing capacities of rectangular concrete columns can be significantly improved by the confinement of multi-spiral hoops (MSHs). The confining effect of multi-spiral hoops on the stress distribution and amplitude of concrete cross section was analyzed by the finite element method. Subsequently, the calculating methods for the axial bearing capacity of rectangular concrete columns in various codes were validated by test data. The deviation of the calculated results of different methods was also analyzed. Based on the results of numerical simulations, the axial compression calculation formulas for MSH confined columns were proposed, and different stress-strain laws were considered for different parts of the concrete cross section. The comparison of test results showed that the theoretical calculation method had better accuracy.