Fatigue and durability behavior of RC beams strengthened with CFRP under hot-wet environment

Real service environment has a significant influence on fatigue and durability behavior of the members since the main reinforced concrete (RC) structural members of bridges are served under vehicle loads and environment coupling action. However, environment and loads were considered separately (uncoupling) in traditional durability experiments. This was different from the real service conditions of the main structural members of bridge. In this paper, three groups of RC beams strengthened with carbon fiber laminate (CFL) were tested under three point bending fatigue loads with uncoupled hot-wet environment (Group A: 50 °C, 95% R.H) and coupled environments (Group B: 50 °C, 95% R.H; Group C: 50 °C, 85% R.H) to discover the effect mechanism on fatigue and durability behavior of RC members strengthened with carbon fiber reinforced polymer (CFRP) under environment and fatigue load coupling and uncoupling action. Moreover, the fatigue test results in atmospheric condition at room temperature (23 °C, 78% R.H) in earlier stage were compared and analyzed. The research results have shown that the hot-wet environmental fatigue equation of strengthened beams that being proposed was effective and feasible. Comparing with traditional environment fatigue experiment (uncoupled), fatigue limit of strengthened beams under coupling action was relatively lower (decreased 20%) in high temperature and humidity environment (50 °C, 95% R.H). The higher load level was, the greater the fatigue life decreased.