Seismic Performance of Hybrid Columns of Concrete-Filled Square Steel Tube with FRP-Confined Concrete Core

An experimental program that investigated the seismic performance of concrete-filled square steel tube with fiber-reinforced polymer (FRP)–confined concrete core (FCCC) column (SCFC) was conducted. Fourteen SCFC specimens were fabricated with four parameters of axial compression ratio, strength grade of concrete, thickness of FRP tube, and thickness of steel tube and tested under constant axial compression and reversed-cyclic lateral loading. Examinations of the test data resulted a number of significant conclusions with regard to the influence of the investigated column parameters on the performance of SCFC columns. Of primary importance, SCFC columns exhibit favorable energy dissipation and ductility, even when the columns were subjected to high axial loads. The results also indicate that SCFC columns delivered satisfactory lateral moment-bearing capacity and displacement ductility under high axial compression ratio. In addition, a good level of average stiffness and equivalent viscous damping ratio were examined. Furthermore, the variations of hoop strains along column height, the relationship of axial displacement–lateral drift ratio, and the plastic hinge length were examined to evaluate the seismic performance of SCFC columns.