Abstract: The coupling damage model of corrosion and fatigue is established considering the interaction between environmental corrosion and fatigue vibration. This model is applied to study the deterioration law of the mechanical property of Q345 equal angles. Firstly, the environmental corrosion model was established according to the annual rainfall time of the target areas, and the evolutionary model for evaluating fatigue damage was presented by combining energy dissipation model with Paris formula of fatigue crack growth. Then, a coupling factor was proposed to effectively measure the relationship between corrosion and fatigue damage. Based on this coupling factor, the coupling damage model was derived by combining the corrosion and fatigue damage models. Finally, the quasi-static test of twenty Q345 equal angles with 70mm×5mm specification was carried out, and the effect laws of the bearing capacity and energy dissipation performance of angle steels under the corrosion, fatigue and corrosion fatigue coupling actions were analyzed, and the coupling damage degradation model of each parameter was established. The results show that the coupling action of corrosion and fatigue promote the development of component damage, but current design specifications and studies rarely consider this effect. The bearing capacity, stiffness, hysteretic curve shape and cycle times of Q345 angle steels changed obviously due to the coupling action of corrosion and fatigue. Moreover, under the coupling action of 12 hours accelerated corrosion and 4.0×104 times fatigue vibration, the degradation rates of ductility coefficient and cumulative energy dissipation parameter were 11.1% and 7.7% more than the total the damage caused by the individual action of corrosion and fatigue damage.

Key words: corrosion fatigue; Q345 equal angles; hysteretic behavior; coupling factor; coupling damage model