Performance and analysis of unidirectional GFRP actively confined high-strength concrete under monotonic and cyclic axial compression

For better understanding the response of unidirectional GFRP actively confined high-strength concrete under dynamic load, this paper mainly investigated the influences of active confinement on the cyclic axial compression performance of high-strength concrete cylinders. The active confinement was produced by the innovative combined action from core concrete expansion and external confinement of unidirectional GFRP at different confinement stiffness. A total of 24 unidirectional GFRP confined high-strength concrete cylinders were tested under monotonic and cyclic axial compression. The results show that the strength enhancement ratio of actively confined high strength concrete cylinders is higher than that of ordinary confined counterparts regardless of the loading modes. In addition, owing to the lateral prestress, the brittle macro cracking of the high strength concrete was reduced. The hoop rupture strain of the actively confined concrete cylinder increases with the increase of the active confinement. The results also show that the stress degradation rate of unidirectional GFRP actively confined high-strength concrete is improved remarkably due to the compactness of core concrete. Guided by the experiments, the high-precision models for the compressive strength and stress-strain relationship of unidirectional GFRP confined high-strength concrete under cyclic axial compression were developed. (C) 2020 Published by Elsevier Ltd.