Behaviour of post-tensioned concrete box girders

Abstract

This paper describes the results obtained to date from a study of the strains developed in two post-tensioned, prestressed concrete box girder bridges both during their construction and subsequent service lives. The instrumentation that was used is described and the simplification and representation of the material properties that were required for the subsequent analysis of the data are discussed. Results are presented for both short-term shrinkage strains developed during the construction of the concrete segments, short-term creep strains developed during the construction of the viaducts and long-term creep and service life strains developed over the 17-year period since their construction. It is shown that the assumptions, which are generally accepted for the design of such superstructures, are valid and that satisfactory predictions of the long-term behaviour can be obtained from analyses based on short-term properties, despite the variable environmental conditions that are likely to be experienced by the structures.