This report describes the measured long-term behavior of a small prestressedconcrete highway bridge. The three spans of about 46 ft (14.0 m) each were madewith precast pretensioned I-section girders and a cast-in-place deck. Strainsand camber were measured in the two instrumented girders for a period of 1067days after transfer of prestress.The measured camber remained small, with values between 0.25 and 0.30 in.(6 to 8 mm) at the last reading. When corrected for the effects of initialtemperature gradients, the camber is about 0.1 in (2.5 mm), while the predictedfinal camber is about 14 in. (3.5 mm).The concrete strains remained relatively small, since the girders in thebridge were not heavily prestressed. The measured strains were in relativelygood agreement with strains computed using an analysis that took into accountthe measured creep and shrinkage properties of the girder and deck concretes.The same analysis indicates that the prestressing force after losses is somewhatlower than the designer assumed, largely as a result of not obtaining thedesired initial forces in the prestressing bed.Creep and shrinkage specimens of both girder and deck concrete were· storedoutdoors in the same environment the bridge was subjected to and in a controlledenvironment laboratory.
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