Compressive behaviour of FRP-confined square concrete columns after creep

This paper presents the results of experimental and theoretical investigations on the stress strain responses after creep of short square concrete columns confined by fiber reinforced polymer (FRP). Creep tests were firstly conducted on four specimens (including two loaded creep specimens and their companion load-free shrinkage specimens) with dimensions of 150 mm×150 mm×400 mm for 312 days, then, after two weeks of creep recovery, these specimens were axially compressed to failure. The comparison of the stress strain curves between the creep specimens and their companion specimens shows considerable effects of creep on the mechanical behaviours of the columns. Based on the microprestress solidification theory for concrete creep and a modified plasticity model, a constitutive model is proposed to predict the behaviour of FRP-confined square concrete columns after creep. The comparison between the model predictions and the experimental results showed good agreement.