A Design Proposal for Concrete Cover Separation in Beams Strengthened by Various Externally Bonded Tension Reinforcements

Abstract

Previous research has shown that the application of externally bonded reinforcements (steel plates, fiber-reinforced polymer (FRP) laminates, overlays, etc.) to strengthen reinforced concrete (RC) beams can lead to brittle debonding failures before the ultimate load is reached. The aim of this study is to develop an analytical approach for the flexural strengthening of existing structures using various types of external reinforcements and predicting the debonding failure. In this study, an analytical model is developed to predict concrete cover separation failure in beams with overlay strengthening that is also applicable to strengthening using other reinforcements, such as steel plates and FRP laminates. An experimental database with various types of beam specimens is used to verify the model’s validity and reliability. A concept for determining the effective strengthening capacity in a strengthening design is presented and the main parameters affecting the strengthening capacity are investigated. Finally, a design proposal is presented for the flexural strengthening of RC beams with respect to concrete cover separation failure. This proposal contributes to the application of external flexural strengthening in practical design.