Stress concentration in beams bonded with FRP composites

Bonding composite materials to structural members for strengthening purpose has received a considerable attention in recent years. The major problem when using bonded FRP or steel plates to strengthen existing structures is the high interfacial stresses that may be built up near the plate ends which lead to premature failure of the structure. As a result, many researchers have developed several analytical methods to predict the interface performance of bonded repairs. This document presents an introduction to composites, their characteristics and application to the strengthening of beams. In addition, a numerical investigation using finite difference method is used to calculate the interfacial stress distribution in beams strengthened with FRP plate having a tapered ends with different thinning profiles. These latter, can significantly reduce the stress concentration. The aim of the numerical analysis is to demonstrate the advantages of use the tapers in design of strengthened beams.