Seismic behavior of hybrid fiber cement-based composites encased CFST columns

The seismic performance of the Hybrid steel-polyvinyl alcohol (PVA) Fiber Cement-based composite (HFC) encased concrete-filled steel tube (CFST) column was investigated by conducting the cyclic loading test on six specimens. The effects of the core concrete strength, steel tube thickness, and axial compression ratio on the seismic performance of the specimens were analyzed. The test results evidenced that increasing the core concrete strength could enhance the capacity and energy dissipation performance of the column but worsen the ductility. In addition, the HFC-encased CFST column with the lower axial compression ratio and thicker steel tube had a better seismic performance. Based on the superposition method and reasonable assumptions and simplifications, the theoretical capacity evaluation model was proposed. Compared with the experimental results, the theoretically predicted bearing capacity of the HFC-encased CFST column presented a high accuracy. In addition, the finite element model was established to numerically study the HFC-encased CFST columns. Validated by the experimental results, the numerical model found that increasing the PVA fiber ratio and steel tube strength grade could greatly improve the seismic performance of the composite columns.