Load-deformation behaviour prediction of timber beams externally reinforced with composite materials

Abstract

Old timber beams have a tendency to weaken with age. In order to repair old timber structures, a rehabilitation technique is required. A rehabilitation method that is getting attention in st~l engineering applications recently involves bonding sheets (or bars) of fibre reinforced polymer c~RP) to the tensile face of the affected beam member to improve its strength and deflection characteristics. This paper presents a prediction model based on the virtual work method and Bazan-Buchanan non-linear constitutive law for timber. The model allows the moment-curvature and load deflection relations of FRP reinforced timber beams to be predicted. The model was verified using experimental results from the literature. A parametric analysis was conducted to show the influence of key parameters such as FRP area and FRP type on the load-deflection characteristics of beams loaded in four point bending. From the model presented here, it is possible to obtain the ultimate load and deflection that each beam can sustain before failure. As expected, the results show that application of an FRP composite to timber beams improves the strength and deflection characteristics of the beam. This indicates that this method may be a quite viable option for the rehabilitation of old timber beam structures.