Effect of surface roughness on cyclic ductility of corroded steel

Stable cyclic hysteretic behavior is required from structural members to dissipate seismic energy. Limited knowledge exists on the hysteretic behavior of corroded steel, and a relationship that quantifies energy dissipation capacity as a function of section thickness and roughness does not exist. Monotonic and cyclic tests of corroded steel were conducted in this research in an attempt to provide such quantification. Results from coupons suggest that assessing the strength of rusted members by machining a smooth coupon from steel extracted from an existing corroded structure, and only using the resulting yield and ultimate strength values in otherwise standard multilinear monotonic models, may be an unconservative approach. Results from cycling tests show that: (1) rusted steel can exhibit a significant hysteretic energy capacity, (2) a linear relationship exists between the total dissipated energy normalized by mean thickness and the mean 10-point-height of irregularities, and (3) increases in roughness correspond to decreases in the magnitude of total normalized energy dissipated before complete failure.