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This paper summarizes a 16-year comprehensive research program carried out at The University of Texas at Austin to identify durability concerns with post-tensioning systems in bridges and to develop durability design guidelines. Major experimental programs examined high performance grouts, segmental joint macrocells, long-term large beam corrosion and long-term column corrosion. After performing comprehensive internal examinations, overall findings indicate unfavorable durability effects due to the use of mixed reinforcement, thin concrete cover, galvanized steel ducts, grout voids and galvanized duct splices. The width of cracks was shown to have a direct adverse effect on specimen performance, and local areas of severe corrosion were found on epoxy-coated and galvanized strands. Favorable behavior was observed, however, for specimens constructed with high-performance concrete, high post-tensioning levels, plastic ducts, and sound, epoxy-filled joints. [ABSTRACT FROM AUTHOR]