Title: External Prestressing: From Construction History to Modern Technique and Technology
Author(s): Michel P. Virlogeux
Publication: Symposium Paper
Appears on pages(s): 1-60
Keywords: box beams; bridges (structures); cable-supported structures; cantilever bridges; composite construction (concrete and steel); concrete construction; history; prestressed concrete; prestressing; prestressing steels; reviews; segmental construction; structu
The development of external prestressing has been one of the major trends in construction during the last 10 years, along with the development of concrete cable-stayed bridges and the increasing use of high-strength concrete. After a historical review, the main principles of the design of externally prestressed bridges are presented. The paper then details the influence of the construction method on the external tendon organization: bridges built span by span, bridges built by the cantilever method or by methods which are mechanically equivalent, and bridges built by the incremental launching method. Some practical problems are presented, such as handling heavy jacks. A last chapter is devoted to composite structures, with concrete top and bottom slabs and steel webs, prestressed by external tendons. French experimental constructions of this type do not appear economically interesting, and prestressing classical composite structures is not yet considered as good a solution for the same reason. But external prestressing is now widely developed for concrete bridges in the United States, France and, more recently, in Belgium, Switzerland, Venezuela, Germany, and Czechoslovakia.