Abstract:
The T-section concrete filled steel and glass fiber reinforced polymer (GFRP) tubular composite column (T-SCFC) is composed of external steel tube, sandwich concrete, GFRP tube and core concrete. Axial compression tests were carried out on 14 confined concrete short columns with different cross-section forms and three groups of concrete-filled steel tubular T-section columns with different wall thicknesses of GFRP tube. The mechanical properties of square concrete filled steel tube (CFST), concrete filled FRP tube (CFFT), steel-concrete-FRP-concrete (SCFC) short columns and T-SCFC columns under axial compression were compared and analyzed. The finite element model with the same size as the specimen was established, and the numerical parameter analysis was carried out to study the influence of steel tube wall thickness and core concrete strength on the axial compression performance of T-SCFC columns. The results show that the built-in GFRP tube can significantly improve the compression performance of concrete filled square steel tubular short columns, and significantly delay the steel yield and buckling of SCFC short columns under axial compression load. Before the peak load, the load-axial displacement curve of T-SCFC column increases bilinearly, and the residual bearing capacity of the specimen maintains high after fracture of the GFRP. The fracture of GFRP can be used as the failure point of the composite column. Increasing the wall thickness of GFRP tube can significantly improve the bearing capacity of the specimen. The calculation results of the finite element model are in good agreement with the test. Increasing the wall thickness of the steel tube can significantly improve the bearing capacity of the specimen. Improving the strength of the core concrete of the specimen only has a certain effect on the equivalent yield load of the specimen, and has little effect on the peak bearing capacity of the specimen.