Behaviour of GFRP-confined sand and cemented sand under four-point flexural tests

Abstract

The use of fibre-reinforced polymer (FRP) composites is on the rise due to their excellent corrosion resistance, making them a viable alternative to traditional piling materials in harsh environments. This paper presents a new glass fibre-reinforced polymer (GFRP) pile that includes an outer GFRP tube filled with sand or cemented sand. Four-point flexural tests are conducted to evaluate the flexural behaviour of the new pile, and the Optical Frequency Domain Reflectometry (OFDR) technique is utilized to capture the longitudinal strain distributions during the tests. The effects of the type of infill material (sand, cemented sand, and fibre-reinforced cemented sand) and the thickness of the GFRP tube (3 mm, 5 mm) are investigated. All experimental results show a significant improvement in the flexural bearing capacity and ductility of the new pile structures compared to the hollow GFRP pile, which can be attributed to the presence of the infill materials. With the increase in the strength of the infill material, the stiffness and strength of the pile increase. The composite action of the ductile FRP composites and the high-ductile infill materials provides enhanced structural performance. A theoretical model is adopted to rationally predict the load–strain behaviour of GFRP-confined cemented sand piles.