Variation of Hoop Strains in Concrete-Filled FRP Tubes with Concrete Strength, Amount of Confinement and Specimen Slenderness

Abstract

This paper presents an experimental investigation on the variation of FRP hoop strains around specimen perimeter and along specimen height. A total of 24 concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs) with circular cross-sections were tested under monotonic axial compression. The CFFT specimens were instrumented with numerous lateral strain gauges attached to the FRP tubes to examine the development of hoop strains along the specimen height and around specimen perimeter. Specimens were manufactured with height-to-diameter ratios (H/D) of 2 or 5, with all specimens maintaining a nominal diameter of 150 mm. Additional test parameters selected for this study included amount of confinement and concrete compressive strength. This paper focuses on the experimentally recorded hoop strains and their variation around specimen perimeter and along specimen height. The results indicate that hoop rupture strains along the height of CFFTs become more uniform for specimens with higher amounts of confinement. On the other hand, the variation of hoop strains around the perimeter of CFFTs was not observed to be significantly influenced by height-to-diameter ratio (H/D), concrete strength or amount of confinement.