Derivation of the bond–slip characteristics for FRP plated steel members

In order to understand the behaviour of steel members retrofitted using adhesively bonded fibre reinforced polymer (FRP) plates, the bond–slip characteristics of the adhesive joint between the FRP and steel must first be established. This is important so that debonding does not occur whilst the members are in service. Previously, purely empirical research on establishing the bond–slip characteristics involved strain gauging the length of the FRP plate, which can lead to a major scatter of results as well as underestimating the peak shear stress. The subject of this paper is to describe a technique for quantifying the bond–slip characteristics based on a structural mechanics approach and which does not require strain gauging the plate. Two types of pull tests and a partial-interaction numerical model are used to quantify the major characteristics of the bond–slip and two types of adhesive are used to illustrate the approach.