Compressive behavior of circular concrete-filled steel tubular columns under freeze-thaw cycles

In this paper, the compressive behavior of circular concrete-filled steel tubular stub columns under freeze-thaw cycles was studied. The influence of different concrete grades and number of freeze-thaw cycles were both investigated through experimental study. The results show that with the increase of the number of freeze-thaw cycles, the axial strength of specimens decreases regardless of concrete grade. The axial strength deterioration of the CFST specimens under different freeze-thaw cycles increases with the decrease of concrete strength, so does the reduction of enhancement factor. The ultimate displacement and the ductility indexes of CFST specimens are barely affected by the freeze-thaw cycles. Based on the test results, a reduction factor k_sr for quantifying the strength reduction of CFST and a factor k_csr for considering the strength degradation of core concrete are proposed to predict the ultimate compressive strength of CFST stub column under freeze-thaw cycles.