Damage Evolution Mechanism of FRP-Constrained RC Columns Under Coupled Wind-Sand-Freeze-Thaw Erosion

Wenhao Ren^*Siha A

• Inner Mongolia University of Technology, Hohhot, China

Reinforced concrete (RC) structures in cold, arid regions are subjected to simultaneous wind-sand erosion and freeze–thaw cycling, resulting in progressive deterioration of mechanical performance. To quantify this coupled degradation and assess reinforcement strategies, laboratory simulation tests were conducted on FRP-strengthened RC columns under controlled wind-freeze conditions (26 m/s sand exposure and −20°C to +20°C thermal cycling). After 200 cy-cles, the compressive and flexural strengths of plain concrete decreased by 32.4% and 36.7%, respectively, whereas CFRP-, BFRP-, and GFRP-reinforced specimens retained 87.2%, 84.6%, and 82.1% of their initial strength. Surface abrasion, pore connectivity, and interface deterioration were identified as primary degradation mechanisms. A hybrid prediction framework incorporating physical constraints and Weibull reliability mapping was developed to simulate long-term strength evolution. Compared with conventional models (ANN, SVR, DT, Bagging, RF, AdaBoost, GB, XGBoost), the proposed framework demonstrated superior predictive accuracy, improving R² from 0.9185 to 0.9764 and reducing RMSE from 1.5458 kN to 0.8976 kN. The incorporation of degradation laws ensured monotonic strength decline and eliminated non-physical oscillatory predictions observed in purely data-driven models. Reliability analy-sis further showed that, after 200 cycles, the reliability index of plain RC columns decreased to 0.25, while FRP-reinforced specimens maintained values above 0.65. This study provides experimental evidence and computa-tional insight into the coupled degradation mechanism of FRP-strengthened RC columns and demonstrates that phys-ically constrained hybrid learning offers an effective and interpretable approach for long-term durability assessment under severe environmental exposure.