Innovative prestressing with FRP sheets: Mechanics of short-term behavior

The short-term mechanical behavior of a novel prestressing technique is described. The technique involves external bonding of pretensioned fiber-reinforced plastic (FRP) composite sheets on the tension zones of structural elements. Analytical models are developed describing the maximum achievable prestress level so that the FRP-prestressed system does not fail near the anchorage zones. Both adhesive layer and beam material failures are considered. It is found that the method's efficiency is improved by increasing the thickness of the adhesive layer and/ or increasing the area fraction of the composite material, efficiency being defined as the level of prestress at the bottom fiber of the member. Moderate to high prestress levels are achieved depending on whether failure of the system is controlled by the shear strength of the beam material or that of the adhesive layer. The technique is applicable to the rehabilitation/strengthening of existing structures as well as the construction of new ones.