Dynamic mechanical response and energy dissipation properties of steel fiber-reinforced concrete under high-temperature damage

This study employed a 75 mm segmented Hopkinson pressure rod (SHPB) device to systematically investigate the dynamic mechanical behavior of steel fiber-reinforced concrete (SFRC) under varying impact pressures. By comparing damage patterns, strain rate-dependent efficiency effects, and energy dissipation characteristics across different fiber contents and temperature conditions, a three-dimensional (3D) mesoscale model was established incorporating polyhedral aggregates, mortar, interfacial slip zone (ITZ), and steel fibers. The mechanisms underlying mechanical property changes in steel fiber-reinforced concrete (SFRC) under high temperatures were further elucidated. The experiments were conducted at four target temperatures (25℃, 200℃, 400℃, and 600℃) with three fiber content levels (0%, 1%, and 2%). Results demonstrated that SFRC's dynamic strength initially increased with rising temperature before decreasing, while also showing an increase with higher steel fiber content. Under identical impact pressures, SFRC's compressive and splitting impact toughness exhibited a trend of initial increase followed by a decrease with elevated temperatures. The addition of steel fibers significantly enhanced SFRC's dynamic compressive strength, elastic modulus, energy absorption capacity, and impact toughness, while effectively suppressing fracture processes. Simulation results showed high agreement between dynamic loading damage patterns and experimental data, validating the accuracy and reliability of the model.