Yield Resistance and Ultimate Resistance of Steel Beam with Random Corrosion Damage

This paper presents a numerical study on the yield resistance and ultimate resistance of steel beam with random corrosion damage. The corrosion is considered by introducing random cylindrical pits to the intact steel beam, in which the thickness of the beam, both at the section and along the length of the beam is reduced. Altogether 240 corroded beams are numerically studied, wherein the effects of corrosion ratio, corrosion diameter, corrosion depth and corrosion location on the yield resistance and ultimate resistance of steel beam are considered. It is found that for global corrosion scenario, when the corrosion ratio is 4.76%, 9.26%, 13.37%, 18.25%, 22.36%, and 25.76%, due to the random nature of corrosion, the reduction factors of ultimate resistance of steel beam range from 0.9–0.92, 0.81–0.86, 0.77–0.8, 0.71–0.76, 0.64–0.67, and 0.58–0.64, respectively. Moreover, when corrosion distributes only at the bottom flange or top flange of steel beam, the adverse effects of bottom flange corrosion and top flange corrosion on the resistance of steel beam are the same. The corrosion diameter and corrosion depth have limited effects on the resistance of steel beam. The relationship between the reduction factors for the yield resistance and ultimate resistance with the corrosion ratio of the beam is proposed. It is found that for the global corrosion case, the reduction factors of the yield resistance and ultimate resistance of the beam are linearly and negatively correlated with the corrosion ratio. For each 10% increase in the corrosion ratio, the reduction factor of yield resistance and ultimate resistance decrease by 18.9% and 15.1%, respectively. The resistances of the corroded beam with random corrosion pits and uniform corrosion are also compared. The results suggest that by using uniform corrosion model, the resistance of the corroded steel beam will be significantly overestimated. When the corrosion ratio is about 14%, the overestimation on the ultimate resistance of steel beam by using uniform corrosion model is more than 10%.