Behavior of concrete-filled GFRP tube columns under cyclic axial compression

Abstract

To study the axial compression performance of glass fiber reinforced polymer (GFRP) tube confined concrete columns, 13 circular cross-section specimens with 5 mm wall thickness and 500 mm height were designed, including six specimens of recycled concrete columns with different GFRP tube diameters, six specimens of high-strength ordinary concrete columns with different GFRP tube diameters, and one GFRP tube were made. Repeated axial compression tests were conducted on all 13 specimens. The failure process and failure mode, load–displacement curve, skeleton curve, characteristic load and displacement, load–strain curve, and load-residual displacement curve of each specimen were analyzed. The results show that the failure trend of recycled concrete columns confined by GFRP tubes is similar to that of high-strength ordinary GFRP tube confined concrete columns; GFRP tubes effectively increased the axial load bearing capacity of components. Finally, GFRP tubes suffered ring failure with the concrete inside being crushed; the axial load bearing capacity of GFRP empty tubes is relatively low with some brittleness characteristics while suffering failure. With the increase in the diameter of GFRP tubes, the load bearing capacity and stiffness of components gradually increase and have a certain degree of ductility. Based on the experimental study, a formula was derived for the axial load bearing capacity of GFRP tube concrete columns. The calculation results are consistent with the experimental results, providing a certain guiding significance for theoretical research and engineering application of GFRP tube concrete columns.