Behaviours of reinforced concrete-filled GFRP tube stub columns under low-temperature axial compression

Abstract

A series of low-temperature tests on axial compression behaviours of 18 stub columns were presented in this paper, which included eight unconfined reinforced concrete columns (URCC) and ten reinforced concrete-filled GFRP tubes (RCFFTs). Regarding the compression tests on RCFFTs, axial compression load was applied to both inside confined reinforced concrete column (CRCC) and GFRP tube. The studied parameters of this paper included low temperatures of 20, −30, −60, and −80 ℃, diameter-to-thickness ratios of 20, 21, 30, 40, and 50, reinforcement ratio of 2.18% and 3.84%, and reinforcement type of steel reinforcement and GFRP bar. The failure modes, axial compression load–strain curves, and compressive stress–strain curves of RCFFTs at low temperatures have been revealed. Meanwhile, the influences of different parameters on the ultimate compression resistance, ultimate compression strength, stiffness, ultimate axial strain, and ultimate hoop rupture strain of RCFFTs at low temperatures were detailly discussed. These results indicated that low temperature generally improved the axial compression behaviours of RCFFTs. According to the test results, prediction formulae have been proposed to determine the ultimate compression resistance and ultimate axial strain of RCFFTs reasonably but conservatively at low temperatures, which considered the influence of longitudinal reinforcements and ties.