Composite strands for prestressed concrete: State-of-the-practice and experimental investigation into mild prestressing with GFRP

Abstract

An overview of available solutions and historic experiences in the state-of-the-practice of prestressing technologies with non-conventional tendons is presented to determine whether mild prestressing with Glass Fiber Reinforced Polymer (GFRP) strands may represent a solution for some of the existing challenges. The experimental portion of this project explores the potential of GFRP strands coupled with traditional steel anchors as an efficient, easy-to-deploy, and non-corrosive pre-tensioning solution in applications that require limited levels of prestress. The strands are composed of seven twisted wires and have a nominal diameter of 15.2 mm. This study on GFRP strand prototypes covers: a) mechanical and geometrical characterization; b) jacking strength of the coupled strand-anchor under instantaneous and sustained load; c) load loss during anchor setting using various pulling techniques; and, d) some flexural properties and coilability. Results should only be considered indicative of the potential of the technology given also the limited material availability. Experimental outcomes are evaluated with reference to information available in archival literature with particular reference to GFRP reinforcing bars.