ABSTRACT
Reinforced concrete combines concrete and steel bars by simply putting them together in a passive manner. Prestressed concrete combines high-strength concrete and high-strength steel in an active manner; this is achieved by tensioning the steel and holding it against the concrete, thus putting the concrete into compression. Prestressed concrete structures, using high-strength materials eectively, give improved serviceability, load-carrying capacity, and durability. It is an attractive alternative for long span bridges, and has been used worldwide since the 1950s. Prestressed concrete bridges have gone from being almost nonexistent in the 1940s to clearly being the predominant bridge type currently; these are being built in the United States and around the world. About 25% of highway bridges are prestressed concrete in the United States (FHWA 2010). ere are three types of prestressed concrete bridges such as precast pretensioning girder bridges, cast-in-place (CIP) posttensioned girder bridges, and segmentally constructed concrete girder bridges. is chapter focuses only on CIP posttensioned prestressed concrete girder bridges. e precast pretensioned presestressed concrete girder bridges are presented in Chapter 1 and segmental concrete bridges are discussed in Chapter 3. For a more detailed discussion on prestressed concrete, references are made to textbooks by Collins and Mitchell (1997), Lin and Burns (1981), Nawy (2009). For precast prestressed concete, see PCI (2011). For posttensioned concrete, see CSI (2008) and PTI (2006).
