A Novel FRP Anchor for Preventing Delamination in FRP Strengthened Concrete Beams

Abstract

<p>To delay the delamination of the externally bonded Fiber Reinforced Polymer (FRP) laminate from the concrete surface and to ensure that after initial delamination the FRP continue to carry some load, a new FRP mechanical anchor system was developed and tested to delay complete delamination in RC beams externally strengthened with FRP laminate. The anchor will be akin to a nail with a relatively flat and wide head and a small diameter shank. It will be inserted into epoxy-filled drilled holes in the concrete while its head will rest on the surface of the FRP laminate and will be adhesively bonded to it. The advantage of this anchor is the ease with which it can be used in different structural elements involving flexural and/or shear strengthening with FRP laminates. The salient feature of the anchor is its wide head to resist high interfacial shear stresses and its shanks that are inserted inside the concrete to provide mechanical anchorage and to resist pullout.</p> <p>A number of full scale RC beams, retrofitted with FRP sheets or laminates will be tested to verify the validity of the concept and the effectiveness of the proposed anchor in delaying/preventing delamination. Different oriented models will be used to calculate the capacity of the tested beams. Finally, a modified model to predict the interfacial shear and normal stresses with and without tension stiffness is presented. The proposed anchor system can eliminate the delamination problem in beams retrofitted for increased flexural strength. It could increase the delamination load and allowed the FRP laminate to reach its full ultimate strength.</p>