This paper presents analytical procedures for determining post-tensioning tendon losses in a typical spliced, precast concrete girder used in the 4500 South Bridge at Interstate 15 in Salt Lake City, Utah. The bridge is composed of eight post-tensioned, spliced, precast concrete girders that have three segments each to produce a single clear span of 61.44 m (201.6 ft). The analysis procedure specified in the American Association of State Highway and Transportation Officials�? AASHTO LRFD Bridge Design Specifications is used and compared with experimental measurements of losses in the post-tensioned, spliced, precast concrete girders monitored at the 4500 South Bridge, as described in the companion paper, “Post-tensioned Tendon Losses in a Spliced-Girder Bridge, Part 1: Field Measurements,�? in the May- June 2007 PCI Journal. The time-dependent method predicts measured post-tensioning losses in the precast concrete girders with sufficient accuracy at the abutments and at midspan. The measured modulus of elasticity of the girder concrete was found to be predicted more accurately by the equation proposed by AC! Committee 363. Concrete shrinkage and creep tests performed on the girders were used to obtain the ultimate creep coefficient and ultimate shrinkage strain. These results were compared with values recommended by AC! Committee 209. Shrinkage and creep tests indicate an asymptotic achievement of ultimate shrinkage strain and ultimate creep coefficient in approximately eight months, a result supported by strain readings from vibrating wire strain gauges embedded in the concrete of the spliced girders.
