Size Effect on Compressive Strength of GFRP-Confined Concrete Columns: Numerical Simulation

The available researches on concrete columns confined with fiber-reinforced polymer (FRP) laminates have not comprehensively addressed the size effect. In this study, a three-dimensional mesoscale simulation approach that can consider concrete heterogeneities was established to explore the size effect of glass FRP (GFRP)-confined concrete columns under axial compression. The influence of constraint ratio and cross-sectional type on the failure of columns was investigated. In addition, the effect of lateral constraint on the nominal compressive strength and the corresponding size effect was quantitatively studied. The simulation results indicate that structural size has a significant influence on the nominal compressive strength of GFRP-confined concrete columns. For the present circular columns, size effect on nominal compressive strength is weakened or even suppressed as the FRP constraint ratio increases. For square columns, the presence of GFRP cannot suppress the size effect on compressive strength, since it cannot provide sufficient constraints. Furthermore, a size effect formula that can quantitatively describe the influence of lateral constraint on the size effect of GFRP-wrapped circular concrete columns was developed. Good agreement between the theoretical results and the simulation results as well as the available test results confirms the rationality of the developed size effect law (SEL).