Seismic performance evaluation on composite frame structures with T-shaped multi-cellular CFST columns

Multi-cellular concrete-filled steel tubular (CFST) columns have been widely used in frame structures for seismic resisting purposes. In this paper, the seismic performance of single-story composite frame structures, consisting of T-shaped multi-cellular CFST (TM-CFST) columns connected with steel beams, was investigated. Four specimens of the composite frame structures under constant vertical compressive loads and quasi-static lateral cyclic loads were tested to explore the hysteretic performance. Refined finite element (FE) models were developed to provide a benchmark modeling approach that was able to accurately capture the mechanical behavior of the composite frame structures. The FE analysis results were compared with those measured from tests, showing satisfactory coincidence between the experimental and simulated results. Hence, the validity of the setup in the FE model was verified. Following the validation of the FE modeling approach, a parametric study was conducted, involving the parameters of axial force ratio, beam-to-column linear stiffness ratio, cross-sectional dimensions of columns and width of frame. On this basis, the seismic performance of the composite frames was investigated by analyzing the characteristics including stiffness, strength, ductility, and energy-dissipating abilities. The TMCFST frames are applicable for low- and medium-rise building structures. In practical designs of the TM-CFST frames, the beam-to-column stiffness ratios should be carefully selected to guarantee that the beam reaches full-sectional plasticity before the column at the beam-column joint, fulfilling the requirement of seismic resistant designs.