Prestress model for shear deformation debonding of FRP- and steel-plated RC beams

Abstract

<jats:p> Adhesive bonding plates to the surfaces of RC structures is a widely accepted form of strengthening or stiffening because of the ease of application and unobtrusive nature of this retrofitting procedure. Design guidelines have identified three major forms of plate debonding, one of which is debonding due to the shear deformation across a critical diagonal crack (CDC). CDC debonding is particularly important in RC beams with stirrups, as they are prone to debond before the shear capacity of the beam is attained. In this paper it is shown that the CDC debonding resistance of a plated RC beam is analogous to the shear resistance of a prestressed beam; a design procedure based on the shear resistance of prestressed beams is developed, and correlates well with 77 plated beam tests. In a companion paper the prestress analogy developed here is taken further: it is shown that code approaches for determining the shear resistance of prestressed beams can be used to predict CDC debonding. This has allowed the development of a simple design procedure for adhesive bonding of plates to any surface of an RC beam. </jats:p>