Prestressing Concrete Structures with FRP Tendons

Description

Fiber-reinforced polymer (FRP) composites have been proposed for use as prestressing tendons in concrete structures. The promise of FRP materials lies in their high-strength, lightweight, noncorrosive, nonconducting, and nonmagnetic properties. In addition, FRP manufacturing, using various cross-sectional shapes and material combinations, offers unique opportunities for the development of shapes and forms that would be difficult or impossible with conventional steel materials. Lighter-weight materials and preassembly of complex shapes can boost constructibility and efficiency of construction. At present, the higher cost of FRP materials suggests that FRP use will be confined to applications where the unique characteristics of the material are most appropriate.

Efficiencies in construction and reduction in fabrication costs will expand their potential market. FRP reinforcement is available in the form of bars, grids, plates, and tendons. This document examines both internal andexternal prestressed reinforcement in the form of tendons.One of the principal advantages of FRP tendons forprestressing is the ability to configure the reinforcement tomeet specific performance and design objectives. FRP tendons may be configured as rods, bars, and strands asshown in Fig. 1.1. The surface texture of FRP tendons mayvary, resulting in bond with the surrounding concrete thatvaries from one tendon configuration to another. Unlikeconventional steel reinforcement, there are no standardizedshapes, surface configurations, fiber orientation, constituentmaterials, and proportions for the final products. Similarly, thereis no standardization of the methods of production, such aspultrusion, braiding, filament winding, or FRP preparation for aspecific application. Thus, FRP materials require considerableengineering effort to use properly. Bakis (1993) has outlinedmanufacturing processes.