ABSTRACT
Factors such as population growth, higher volumes of commuter and freight traffic and heavier vehicles have increased the demands placed on existing bridges throughout Australia. Alongside the necessity for structural rehabilitation and strengthening in order to prolong the service life and increase the safety of existing bridges, many innovative materials such as advanced fibre reinforced polymer composites (FRPs) have become popular as a means to strengthen existing reinforced concrete (RC) members in flexure, shear and torsion, via bonding of the FRP to the external surface of the member. Despite the many advantages of FRP materials, a commonly documented failure mode is premature debonding of the FRP from the concrete substrate. It is well understood that the bond strength between the FRP and concrete members can be improved when sufficient anchorage is provided thereby preventing the critical mode of FRP failure. Anchorage systems have the potential to significantly improve the bond performance of FRP systems thus permitting higher levels of strengthening at a fraction of the cost. To date the authors have researched the patch anchors concept which consists of bi-directionally oriented fibre sheets bonded to the surface of the FRP strengthening and the adjacent primarily through a series of FRP-to-concrete joint direct shear tests. More recently, the patch anchors were implemented in the shear strengthening of a large scale prestressed beams for the first time which takes into account omitted factors in joint assemblies such as: size effect, combined flexural/shear stresses, diagonal shear cracking (potentially intersecting the FRP within the anchorage zone) and other failure modes such as web shear crushing or concrete crushing. An evaluation of patch anchor performances in large-scale beam applications will be presented in this paper long side a comparison of results between joint assemblies and full-scale implementations.
