Technological peculiarities of strengthening RC members with prestressed FRP laminates

Abstract

There is a general agreement on the benefits of using FRP materials for structural retrofitting. Full potential of this high strength materials can be implemented by the process of prestressing. However, prestressing has a number of nuances and can be compromised. Therefore, based on the results of a recent experimental study and the experience of other authors, the peculiarities and issues of application FRP reinforcements are summarized. Current paper includes the steps from the surface preparation, anchoring to commissioning. Also, a novel prestressing system for retrofitting of reinforced concrete members with externally bonded FRP laminates is disclosed. The proposed system consists of three main items: a clamping unit, a light frame for hydraulic jack and anchoring plates. The new approach to the use of tempered steel grips for efficient clamping of FRP laminates is presented. Usually, the result of using corrugated surface steel grips would be fractured laminate, therefore plane surfaces are common in commercially available prestressing systems. The advantage of the proposed system lies in the fact that efficient corrugated surfaces are employed for compression of FRP reinforcement.