FE Investigation of Material and Preload Parameters on FRP Strengthening Performance of RC Beams II: Results

The effectiveness of FRP rehabilitation of deteriorating and under-strength reinforced concrete beams depends not only on the properties of the FRP material, but also on the characteristics of other materials in the system, characteristics of the bond, and the relative nature of properties of materials at the interfaces. Response is also affected by the cracked condition of the beam prior to the external bonding of the FRP. This paper reports on a fundamental investigation into the effect of various design parameters using a finite element analysis approach, which not only provides characteristics of response but also enables identification of damage mechanisms and their progression to failure. It is shown that the highest level of strengthening is not always due to use of maxima of the parameters, but rather on the interaction between them. Interface bond strength and fracture energy are shown to have a significant effect on load capacity, ductility and transition of failure modes from debonding within concrete, to FRP rupture, and to debonding within the adhesive itself.