Thread Content
Steel bridges feature large spanning capacity, high strength, fast construction speed, and short construction periods. The completion of the Wuhan Yangtze River Bridge in 1955 established the first monument erected by the Chinese people to their conquest of the Yangtze River ； In recent years, as **infrastructure construction has accelerated, large-scale steel structure bridges have emerged one after another. For the construction of an extra-large steel bridge spanning a river or sea, the amount of steel required is generally tens of thousands, or even over 100,000 tons. Corrosion, stress corrosion, and corrosion fatigue are among the major reasons that cause such large steel bridge components to cease functioning and have their service life reduced. In the 1920s and 1930s, developed countries in Europe and North America built some steel bridges. Since corrosion prevention technologies at that time could not provide long-term protection against corrosion, these bridges suffered severe corrosion once put into use. Even regular painting for maintenance did not offer satisfactory protection, forcing these bridges to be used at a reduced capacity or requiring the construction of a second bridge, which caused huge economic losses ； In 1967, a steel bridge between Happy Point and Noga in the eastern United States collapsed into the Ohio River after 40 years of use, resulting in 46 deaths. Investigations revealed that the cause of the collapse was stress corrosion cracking induced by atmospheric corrosion. For this reason, the corrosion of steel bridges has attracted great attention from various countries. According to reports from 1997, the Wuhan Yangtze River Bridge required maintenance costs of over 1 million yuan per year, yet this amount was still far from sufficient ； Corrosion not only wastes a great deal of manpower and resources but also significantly shortens the service life of bridges. The corrosion protection of bridge steel structures is increasingly becoming a matter of concern. Only by providing effective corrosion protection during its design and construction can the long service life of steel bridges be ensured.