International Concrete Abstracts Portal

Title: CRC #54: DEVELOPMENT OF ANCHORAGE SYSTEM FOR FRP STRENGTHENING APPLICATIONS USING INTEGRATED FRP COMPOSITE ANCHORS

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Publication: CRC

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Keywords: composite, anchors, frp

Date: 10/1/2012

Abstract:
Over the past three decades the use of externally bonded fiber-reinforced polymer (FRP) materials for structural strengthening applications has become an accepted and widely used method. A primary concern of FRP structural strengthening systems is that FRP sheets may debond from the concrete surface at a force significantly lower than the strength of the FRP material. Debonding failures are often brittle and occur with little warning, therefore making them an undesirable failure mode. Past research studies have concluded that fastening FRP sheets with FRP anchors is an effective method for delaying or preventing debonding failures. There is, however, scarcity of research pertaining to fastening FRP sheets with FRP anchors, and a corresponding lack of design guidance. The primary objective of this research program was to better understand the behavior of bonded FRP sheets that include FRP anchors as a supplemental system to prevent debonding. The outcome of this research project will provide data for future development of design recommendations of this type of anchorage system of FRP sheets. This report concentrates on carbon fiber unidirectional sheets applied using a wet layup approach. Test variables that were investigated include: type of the FRP sheet by including two different FRP material manufacturers, bonded sheets without supplemental FRP anchors, bonded sheets with supplemental FRP anchors, number of anchor rows and spacing between rows, number of sheet plies (single or double), and length of bonded sheet behind the anchors. Sixteen laboratory specimens were fabricated and tested. Experimental results show that FRP anchorage systems are very effective in increasing load capacity by delaying debonding. Finite element models of anchored and unanchored FRP sheets were developed to provide a methodology that can be used to expand the laboratory results to elements where anchors are applied using other configurations. In combination with the laboratory results, the finite element models provided a better understanding of the stress distribution within the FRP sheet as affected by the presence of FRP anchors.