Title: Properties of Polyaramid Ropes and Implications for Their Use as External Prestressing Tendons
Author(s): C. J. Burgoyne
Publication: Symposium Paper
Appears on pages(s): 107-124
Keywords: beams (supports); corrosion resistance; creep properties; durability; fatigue (materials); modulus of elasticity; plastics, polymers and resins; prestressed concrete; prestressing; strength; stress relaxation; thermal properties; Design
Paper describes the properties of parallel-lay ropes with a polyaramid (Kelvar 49) core, with particular reference to the long-term properties that are important to the designers of prestressing systems. The anchorage and prestressing systems are described, and results are given for stress-strain, relaxation, creep, stress-rupture, and fatigue behavior. Durability and thermal response are also considered, and it is inferred that the lack of corrosion, in addition to the high strength and high stiffness, makes these materials ideal for use as prestressing tendons where the concrete cannot be used to provide corrosion protection to steel. Descriptions are given of tests on beams prestressed with external tendons, showing that a ductile response can be achieved in a beam made from two brittle materials. It is concluded that these materials will extend the range of structures that can be built with prestressed concrete, and will at last allow the realization of the full potential of externally prestressed concrete.