Numerical analysis of preloaded FRP-strengthened concrete columns under axial compression

Abstract

A finite element (FE) analysis is performed in this paper to investigate the compressive behavior of FRP-strengthened concrete columns under preload by using ABAQUS software. First, the hardening/softening rule in Concrete Damaged Plasticity Model (CDPM) is modified based on the existing experimental data to introduce the preload effect on FRP confinement, and the FE model for FRP confined concrete under preload is established by adopting the operation of element deactivation and reactivation in ABAQUS. Then, the specific influence of preload on the mechanical performance of FRP confined concrete (FCC) during the entire loading process is explored in detail. The numerical results show that preload significantly reduces the increasing rate and amplitude of confinement stiffness for confined concrete in the plastic stage, leading to a relatively low improvement of axial stress of concrete. An extensive parametric analysis is also conducted based on the validated FE model to explore the effect of concrete compressive strength, confinement stiffness of FRP, and preloading rate on the behavior of preloaded FCC. Finally, two new models are proposed to evaluate the dilation behavior and axial stress–strain response of FCC under preload respectively, and the comparisons between theoretical and test results reveal that satisfactory accuracy can be achieved for the two developed models.