Strengthening of Deteriorated Concrete Bridge Girders Using an External Posttensioning System

In this paper, the author discusses how an external posttensioning (PT) system is used to strengthen bridges. A detailed case study of PT strengthening of a Chicago bridge is presented. The article discusses active and passive strengthening techniques, including the introduction of external forces on structural members (active technique) and the use of reinforced concrete (passive technique). The disadvantages and limitations of PT are also discussed, including the fact that posttensioning can only be applied if the concrete is in good condition and capable of withstanding the stress of the PT cables. The author concludes that the use of PT, while improving the strength of bridges, also helps to improve both bridge service life and durability.