Testing of Two 50-Year-Old Precast Post-Tensioned Concrete Bridge Girders

Abstract

This article reports on a study of two 50-year-old, 45 ft (13.7 m) long precast, post-tensioned concrete bridge I-girders that were tested to determine their ultimate strength and to verify the performance of similar girders remaining in service. The girders were post-tensioned with four 1 1⁄8 in. (29 mm) diameter steel bars. A small section of the concrete deck slab was attached to the top flange of the girders at the time of testing. The condition of the girders was judged to be good with the exception of longitudinal cracks in the concrete running along the post-tensioning bar and small pieces of the bottom flange that were broken during transportation of the girder. Further, a part of the deck slab adhering to the top of the girders was severely deteriorated. Cracking of the girders during testing was limited along the length of the girders, consisting of two or three major cracks forming in each girder that opened wide as the girders approached failure. The authors conclude that the tested capacity of the girders was still sufficient to carry anticipated loads, both at service and at ultimate limit states. The tested cracking strength of beam indicated that girders still in service have sufficient strength to carry the service design truck loads without cracking.