Compressive behavior of square and rectangular high-strength concrete-filled FRP tubes

Abstract

This paper presents results of an experimental study on behavior of square and rectangular high-strength concrete (HSC)-filled fiber reinforced polymer (FRP) tubes (HSCFFTs) under concentric compression. The effects of the tube thickness, sectional aspect ratio and corner radius on the axial compressive behavior of concrete-filled FRP tubes (CFFTs) were investigated experimentally through the tests of 24 CFFTs that were manufactured using unidirectional carbon fiber sheets and high-strength concrete (HSC) with 78 MPa average compressive strength. Test results indicate that sufficiently confined square and rectangular HSCFFTs can exhibit highly ductile behavior. The results also indicate that HSCFFTs having tubes of low confinement effectiveness may experience a significant strength loss at the point of transition on their stress-strain curves. It was observed that the behavior of HSCFFTs at this region differs from that of normal-strength CFFTs and it is more sensitive to the effectivness of confining tube. Examination of the test results have also lead to a number of important observations on the influence of the key confinement parameters, which are presented and discussed in the paper.