Experimental study on the axial compression behavior of columns confined by BFRP ties

Few studies have investigated concrete columns reinforced with basalt fiber-reinforced polymer (BFRP) ties. Due to its cost effectiveness, manufacturability, and good corrosion resistance, BFRP should be considered for use in concrete columns. This study experimentally investigated the axial compression behavior of concrete columns longitudinally reinforced with steel bars and transversely reinforced with BFRP ties. The test variables included the fie type, spacing, diameter, and configuration, the longitudinal bar type and the concrete strength. The test results indicated that the steel ties were better than the BFRP ties in enhancing the concrete strength and ultimate load, whereas the BFRP ties improved the post-peak ductility. A smaller fie spacing effectively improved the strength and ductility, and a larger BFRP fie diameter was more beneficial for improving ductility than load capacity. The combination of outer and inner rectangular BFRP ties was best for ductility improvement. M the peak load, the BFRP bars carried far less load than the steel bars; however, the BFRP or hybrid bars provided better ductility. Increasing the concrete strength grade increased the load capacity and decreased the ductility of the column.