Title: Innovative System for Prestressing Fiber-Reinforced Polymer Sheets

Author(s): Raafat El-Hacha, R. Gordon Wight, and Mark F. Green

Publication: Structural Journal

Volume: 100

Issue: 3

Appears on pages(s): 305-313

Keywords: anchorage; beam; carbon fiber-reinforced polymer; concrete; prestressing; strength; temperature

DOI: 10.14359/12605

Date: 5/1/2003

Abstract:
The effectiveness and feasibility of a technique to strengthen damaged concrete beams using prestressed carbon fiber-reinforced polymer (CFRP) sheets has been investigated. This is an ideal technique because it combines the advantage of using noncorrosive and lightweight advanced composite materials in the form of bonded fiber-reinforced polymer (FRP) sheets with the high efficiency offered by external prestressing. A practical and innovative mechanical anchorage system was developed to directly stress the CFRP sheets by jacking and reacting against anchors mounted on the web of the existing concrete beam. The anchorage/prestressing system was applied on 1/3 scale precracked concrete beams. The effect of short- and long-term exposure at room (+22 °C) and low (–28 °C) temperatures was examined, with particular emphasis on identifying any material or prestress changes due to temperature variations that would affect and cause a change in flexural behavior of the strengthened beams. The developed anchorage system was successful and easy to apply and proved to be a feasible and practical method for prestressing CFRP sheets. No damage in the bond between the sheets and the concrete was observed at low temperature under short- and long-term exposures. The prestressing levels in the CFRP sheets were sufficiently maintained when subjected to long-term exposure at both room and low temperature.