Spiral strands, galvanized steel wires, galvanized semiparallel wire strands, and steel tie rods in large-span building structures are inevitably corroded due to long-term exposure to corrosive atmospheres. However, research on different structural cables is rare, and lifetime safety evaluation of large-span building structures is urgently required. Therefore, three corrosion tests and static tensile tests after corrosion of four types of structural cables were conducted to determine the effects on corrosion behavior caused by plating, coating, twisting, and the environment. The corrosion behavior of a cable had different characteristics. A calculation method for the uniform corrosion depth of semiparallel wire strands and a three-parameter power function that effectively expresses the relationship between corrosion depth and exposure time were proposed and verified. The equivalent conversion relationship between the atmospheric exposure test and the standard laboratory accelerated corrosion test was established. The recommended 50-year corrosion depth for different structural cables was calculated, based on two corrosive environments in which long-span building structures often exist.