Axial-flexural behaviours of concrete-filled square GFRP tubular columns under low temperatures

This study reported experimental investigations on the axial-flexural behaviours of concrete-filled square glass fiber-reinforced polymer (GFRP) tubular (CFSFT) columns at low temperatures. Twenty CFSFT columns under eccentric loads and two-point loading were conducted to evaluate the influences of low temperatures (T = 20 and -60 degrees C) and eccentricity ratios (e/r = 0.00, 0.25, 0.50, and 0.75). Failure modes, load-displacement behaviours, and load-strain behaviours at low temperatures have been reported. Test results indicated the load-vertical displacement curves of CFSFT columns under eccentric loads exhibited three different stages, i.e., linear, tran-sition, and strain hardening or softening stage. Meanwhile, the bilinear load-deflection curves were observed for CFSFT columns under four-point bending. Based on these test results, the experimental axial load-moment (NT -MT) curves of CFSFT columns were obtained. These curves indicated that decreasing the temperature from 20 to -60 degrees C observably increased both the ultimate axial load (NuT) and ultimate bending moment (MuT) of CFSFT columns. However, the increment of both ultimate axial load and ultimate bending moment gradually decreased with the increasing eccentricity ratios.

Automated summary

This study experimentally investigated the behavior of concrete-filled square GFRP tubular columns at low temperatures. The effects of low temperatures and eccentricities were evaluated using 20 CFSFT columns subjected to eccentric loads and two-point loading. Test results showed three stages in the load-displacement curves under eccentric loads and observed bilinear load-deflection curves under four-point bending. The ultimate axial load and ultimate bending moment of the CFSFT columns increased with decreasing temperature but with a decreasing increment as eccentricity ratios increased.