Dynamic Mechanical Properties and Damage Constitutive Model of Frozen–Thawed Basalt Fiber-Reinforced Concrete Under Wide Strain Rate Range

To comprehensively investigate the compressive behavior of basalt fiber-reinforced concrete (BFRC) subjected to multiple freeze-thaw cycles, a series of quasi-static and dynamic compression tests were conducted on BFRC at various fiber volume fractions and a wide strain rate range of 1 × 10^-3-420 s^-1. The freeze-thaw deterioration characteristics of BFRC were analyzed from macro and micro perspectives. The influence of freeze-thaw degradation, strain rate effect, and fiber reinforcement effect on the mechanical performance of BFRC was investigated. It was found that when the fiber volume fraction was 0.2%, the fiber reinforcement performance of basalt fiber was optimal. By incorporating the damage factor of freeze-thaw cycles and the dynamic increase factor of strength into the Ottosen nonlinear elastic constitutive model, a dynamic constitutive model that considers the fiber content, strain rate enhancing effect, and freeze-thaw degradation influence was established.