Behaviour of preloaded concrete cylinders confined by fibre-reinforced polymer composites

Abstract

The stress–strain behaviour of concrete confined by fibre-reinforced polymer (FRP) is an important part of studying the seismic rehabilitation of concrete structures. Most previous studies have investigated the stress–strain behaviour of concrete prisms confined by polymer composites without preloading, but concrete columns are under various loading conditions before being retrofitted with polymer confinement. Therefore, in this study, FRP-confined concrete cylinders with different preloading ratios were prepared to examine the effect of preloading on the behaviour of retrofitted concrete columns. The results indicated that preloading affects important points of stress–strain curve. Preloading up to 75% of the unconfined concrete strength had a positive effect on the stress–strain behaviour, but 90% preloading reduced the strength of the FRP-confined concrete. A modification for the stress–strain models of preloaded FRP-confined concrete is thus suggested.