On the up side, he feels the technology has matured and developed for flexural strengthening and that future opportunities exist in shear strengthening and combinations with other strengthening technologies.

Project: FRP in Strengthening Steel Structures
School: North Carolina State University
Location: Raleigh, North Carolina
Director: Sami Rizkalla

When you consider the notion of using fiber-reinforced polymers (FRP) for strengthening and repair of structures, those structures are usually concrete. But North Carolina State University (NCSU) Professor Sami Rizkalla wanted to look beyond that, and apply the technology to steel structures. “The majority of civil infrastructure involves steel, so it makes sense to try and use FRP to strengthen those structures,” he says.

Rizkalla first worked with a company to produce high-modulus carbon, which adds stiffness due to being twice the elastic modulus of steel. Next, studies were done to select appropriate adhesives for repair, and testing was done using a model bridge made of steel beams and composite action with concrete.

Testing ultimately led the team to design a guideline on how to strengthen steel structures with FRP. “This guideline was sent to the International Institute for FRP in Construction’s (IIFC) technical committee on FRP-strengthened metallic structures. They reviewed and edited it and now we are close to a final guideline,” says Rizkalla.