Finite element analysis of concrete-encased columns reinforced with multiple steel sections

Concrete-encased columns reinforced with one built-up steel core are widely used as mega columns in high-rise buildings. Due to the enormous size of the steel core, multiple steel segments have to be welded and spliced on-site, which might inflict detrimental impacts on the integrity and ductility of the columns. To solve this practical issue, one method using multiple steel sections to replace one gigantic built-up section is proposed. However, whether those columns reinforced with individual steel sections could have the same capacity as the ones reinforced with one steel core and whether the current design method relying on strain compatibility is still applicable to design such columns remain unknown. In this study, one column specimen reinforced with multiple steel sections is tested and the test results are utilized to calibrate finite element models. Afterward, finite element (FE) analysis is performed on concrete-encased columns reinforced with multiple steel sections to numerically examine the load capacity of those columns. Based on the numerical analysis, a design method based on modified strain distribution is proposed. Numerical results indicate that concrete-encased columns reinforced with multiple steel sections exhibit similar performance compared with the one reinforced with one steel core, showing great potential to be applied as mega columns in high-rise buildings.