Effect of strain rate on the stress–strain behavior of FRP–confined concrete cylinders: review and model

Existing dynamic stress–strain models for fiber–reinforced polymer (FRP)–confined concrete do not adequately consider the strain rate effects on concrete and FRP during these models’ development. This study thoroughly investigates the influence mechanisms of strain rates on the mechanical properties of concrete and FRP, then proposes an accurate stress–strain model. A comprehensive database was established by compiling experimental data from published literature, encompassing 969 plain concrete specimens, 330 FRP specimens, and 184 FRP–confined concrete cylinders. The database encompasses strain rates ranging from 10⁻⁶s⁻¹to 338 s⁻¹. From this database, models on dynamic compressive strength, dynamic elastic modulus, and dynamic peak strain models for plain concrete, along with a dynamic tensile strength model for FRP, were developed. Analysis of the stress–strain curves in the database reveals that the stress–strain curves of FRP–confined concrete transition from a two–stage to a three–stage pattern when the strain rate increases. Finally, a novel stress–strain model was proposed considering the coupled strain rate effects of concrete and FRP. Validation results demonstrate that the newly developed model can effectively predict the mechanical responses of FRP–confined concrete cylinders across varying strain rates.