FRP-strengthened and all-FRP structures paper
Vincent, T & Ozbakkaloglu, T 2014, 'An experimental study on the effect of concrete shrinkage on compressive behaviour of high-strength concrete-filled FRP tubes', in ST Smith (ed.), 23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23), vol. I, Byron Bay, NSW, 9-12 December, Southern Cross University, Lismore, NSW, pp. 465-470. ISBN: 9780994152008.
Fibre reinforced polymer (FRP)-confined concrete has received significant research attention over the last two decades, with recent experimental studies identifying significant benefits offered by FRPconfined high-strength concrete (HSC). However, studies examining the influence of concrete shrinkage on the behaviour of FRP-confined concrete remain limited, with no reported study to date examining this influence on HSC specimens. Concrete shrinkage may pose a concern for concrete-filled FRP tubes (CFFTs), as in these members the curing of concrete takes place inside the FRP tube. This paper presents an experimental investigation on the influence of FRP-to-concrete interface gap, caused by concrete shrinkage, on axial compressive behaviour of FRP-confined HSC. A total of 18 aramid FRP (AFRP)- confined concrete specimens with circular cross-sections were manufactured. 3 of these specimens were instrumented to monitor long term shrinkage strain development and the remaining 15 were tested under monotonic axial compression. The influence of concrete shrinkage was examined by applying a gap of up to 0.12 mm thickness at the FRP-to-concrete interface, simulating 1600 microstrain of shrinkage in the radial direction. The results of this experimental study indicate that the influence of interface gap on axial strain enhancement is significant, with an increase observed as the gap increased. Conversely, the influence of interface gap on axial strength enhancement is found to be small with a slight reduction observed with increased gap. It was also observed that an increase in interface gap increases the tendency for a drop in axial stress at the transition region of axial stress-strain curves.