FRP-confined rubber concrete with effect of strain rate : tests and analysis-oriented stress-strain model

Rubber concrete is attracting more and more investigations and applications in recent years, due to its environmental advantages and lightweight performance. As the replacement by rubber particles can reduce the concrete strength, an efficient and lightweight solution for strengthening and repairing rubber concrete is to apply fiber-reinforced polymer (FRP) confinement. This paper is the first to consider the influence of strain rate on the stress-strain relationship of rubber concrete with FRP confinement. To develop a stress-strain model of FRP-confined rubber concrete under different strain rates, an experimental program with 36 FRP-confined concrete specimens was conducted in this work. In the experiments, rubber particles were used to replace 0-30 % fine aggregates by volume. Strain rates of 3.3 × 10-5/s, 3.3 × 10-4/s, and 3.3 × 10-3/s were used to simulate three different strain rate levels of quasi-static loading, fast loading, and seismic loading, respectively. The experimental results showed that the compressive strength of FRP confined rubber concrete obviously increased with the strain rate increases, and decreased with an increasing rubber replacement ratio. Based on the experimental results, this paper proposed analytical models to predict the lateral strain-axial strain relationship, peak strength, and peak strain for FRP confined rubber concrete considering the strain rate influence. Finally, an analysis-oriented stress-strain model of FRP confined rubber concrete under different strain rates was established. The predicted results of the analysis-oriented stress-strain model showed good agreement with the experimental data.