Behavior of FRP-confined sea-sand concrete columns with a prefabricated concrete-filled FRP-steel core

Abstract

Adopting fiber-reinforced polymer (FRP) composites as a confining device and a protective skin not only allows usage of sea-sand concrete which is generally forbidden in conventional steel reinforced concrete structures, but also leads to enhancement of concrete strength and deformation capacity. This paper presents a pilot study on axial compression tests on hybrid FRP-confined sea-sand concrete columns with a prefabricated concrete-filled FRP-steel tube core (simply referred to as FRP-Confined Sea-sand Concrete-Prefabricated Core Columns or FCSC-PCCs). The prefabricated concrete-filled glass FRP (GFRP)-steel core, serving as reinforcing core in FRP-confined concrete columns, is expected to enhance the FRP-confined concrete columns and enable to make use of sea-sand in the concrete between the two tubes. Effects of the steel tube diameter, the GFRP tube thickness and the thickness of the external Carbon FRP (CFRP) tube are carefully investigated. The axial load–axial strain curve of FCSC-PCCs as well as the confined concrete in FCSC-PCCs generally exhibit a monotonically ascending behavior owning to the confinement from the external CFRP tube and the internal FRP-steel composite tube. A new model for average ultimate axial stress and axial strain of confined concrete in FCSC-PCCs is established and the comparisons demonstrate that the proposed model is of satisfactory accuracy.

Keywords

• Concrete-filled FRP-steel tubes
• Sea-sand concrete
• Hybrid column
• FRP-confined concrete
• Axial compression