Experimental investigation of FRP-confined HSC-filled steel tube stub columns under axial compression

In this study, the axial compressive properties of fiber-reinforced plastic (FRP)-confined high-strength concrete -filled steel tube (HSCFST) stub columns were investigated, and the effects of the steel tube thickness, FRP type, concrete strength, and number of FRP layers were analyzed. The results reveal that fracturing of the FRP and bulging deformation of the steel tube are apparent when the stub column fails. An increase in the concrete strength, thickness of the steel tube, and number of FRP layers effectively improve the ultimate strength of the stub column. Compared with carbon fiber-reinforced plastic (CFRP), glass fiber-reinforced plastic (GFRP) has a more evident effect on improving the ultimate strength and delaying the stiffness degradation of stub columns. Further, a finite element model that accurately simulates the axial compressive behavior of FRP-confined HSCFST stub columns was established to better understand the stress development of the high-strength con-crete (HSC), steel tube, and FRP. In addition, a calculation method for the peak strain and ultimate strength of FRP-confined HSCFST stub columns subjected to axial compression loads was developed; this method can accurately predict the actual test results.

Automated summary

In this study, the axial compressive properties of FRP-confined HSCFST stub columns were investigated, and the effects of steel tube thickness, FRP type, concrete strength, and number of FRP layers were analyzed. The results showed that increasing the concrete strength, steel tube thickness, and number of FRP layers effectively improved the ultimate strength of the stub columns. GFRP showed a more significant effect on improving the ultimate strength and delaying the stiffness degeneration compared to CFRP. A finite element model was established to accurately simulate the axial compressive behavior of FRP-confined HSCFST stub columns and a calculation method for the peak strain and ultimate strength was developed.