ABSTRACT
During the last three decades, unbonded post-tensioning has progressively become the predominant construction choice for commercial concrete buildings in the United States. The utilization of unbonded tendons is now standard practice for concrete structures. Because of their excellent performance record and their economical and versatile application, the total use of unbonded tendons increased from approximately 7500 tons in 1976 to over 180,000 tons of prestressing steel in 2005, adding up to over 1 billion square feet of slab constructed with unbonded post-tensioning. Early applications of unbonded tendons and their limitations in design and construction were soon succeeded by well-established analysis, design, detailing, and field procedures. Driven by durability considerations, post-tensioning
manufacturers have implemented product improvements for corrosive environments. The most meaningful testimony for unbonded post-tensioned construction is the successful performance of over 1 billion square feet of concrete construction.
