| Description |
Prestressed concrete has been a significant contributor to the success of modern civil engineering projects because it allows longer spans and lighter members to be constructed. Despite the usefulness of prestressed concrete, a major disadvantage is the susceptibility of steel prestressing tendons to corrosion. Corrosion can be accelerated by vehicular impact damage which removes concrete cover, exposing the tendons to the elements. If damaged members can be repaired with fiber reinforced polymer (FRP) composites, total replacement of the structure can be avoided. FRP composites are excellent candidates for use in prestressing because of their light weight, superior resistance to corrosion, and comparable strength to steel. Post-tensioned external FRP tendons can be implemented to restore capacity lost through corrosion or damage or meet increased load requirements; however, there are three obstacles that have hindered wide implementation of external FRP post-tensioning in rehabilitation and retrofit applications. The following obstacles inhibit implementation: the lack of a suitable anchorage device to maintain the post-tensioning force in the FRP tendons, the lack of an innovative stressing device that reduces the requirement for a significant amount of free space behind the post-tensioned member, and the lack of design equations detailing the use of FRP tendons for field applications. This research involves overcoming the three aforementioned obstacles. The first part of this research is concerned with the development of a unibody clamp anchor that controls slip and stress concentrations in post-tensioned carbon fiber reinforced polymer (CFRP) rods. Additionally, finite element modeling was employed to conduct a relative comparison of the anchor performance across four different design generations. A second objective of the research was to design and implement a simple mechanical stressing device and the unibody clamp anchors to damaged reinforced concrete beams controlled by shear and damaged prestressed concrete beams controlled by flexure. The final objective considered in the research was an evaluation of design equations from the literature. In short, this research as a whole demonstrates the ability to utilize external post-tensioned CFRP rods for structural repair applications, and forecasts their potential for more widespread use. |
