In Situ Concrete Bridge Strengthening Using Ductile Activated NSMR CFRP System

Novel and complex structural solutions are often challenging to introduce in the building industry since they may provide unconventional and less verified behavior combined with several novel and unique failure modes. A desired safety level may be difficult to verify due to the lack of knowledge related to failure modes and their variation. This study introduces a method that may provide a first step toward addressing such challenges. Five laboratory tests were done on a novel ductile response-controlled anchor system used for prestressed CFRP NSMR strengthening. These results were used as a basis for further implementation in a pilot project where an in situ cast concrete bridge was strengthened with the developed system. A particular focus was dedicated to the capability of the designed system response to provide a consistent load/deformation curve, yielding threshold, and yielding regime. The novel system enabled response tailoring to the specific pilot project. Installation and prestressing procedure worked as desired, where losses in the fully prestressed system, after three weeks, were approximately 0.2 to 1.6 kN (0.2–1.3 mm). In situ proof loading of all strengthening systems (20 anchor systems) was done to eliminate any possible failure modes below the proof-loading level. It was performed with no signs of distress.