FRP Tubes Filled with Reinforced Concrete Subjected to Cyclic Axial Loading

Abstract

Infrastructure safety, durability, and serviceability have been significantly enhanced as a result of improved construction materials over the past two decades. Concrete-filled fibre-reinforced polymer (FRP) tubes (CFFTs) system is one of the most promising technique to protect the reinforced concrete structures from aggressive environmental conditions. Most of the experimental investigations performed on CFFT columns have focused on short, unreinforced, small-scale concrete cylinders, tested under monotonic axial loading. In contrast, only few studies have so far investigated the effects of the internal longitudinal reinforcement type (steel or FRP bars) on the behavior of CFFT long columns. This paper presents preliminary test results of an experimental study on the behavior of concrete-filled FRP tube (CFFT) columns internally reinforced with steel and FRP bars. Six reinforced concrete (RC) and CFFT columns were constructed and tested until failure. The test parameters were: (1) internal reinforcement type (steel, glass FRP (GFRP), and amount, and (2) GFRP tube thicknesses. All columns had 1900-mm in height and 213-mm in diameter. Examination of the test results has led to a number of significant conclusions in regards to the trend and ultimate condition of the axial stress-strain behavior and mode of failure of tested CFFT columns. These results are presented, and a discussion is provided on the influence of the main test parameters in the observed behaviors.