Timber Beam Bearing Reinforcement with GFRP Glued-In Plates: Strength and Hydrothermal Effects

Abstract

This paper presents a simplified method of analysis and design for the repair of deteriorated timber beam ends using glass fiber–reinforced product (GFRP) bonded rigid plates. It assesses the load-bearing capacity of the plate-timber connection and assumes two failure modes: shear stresses at the bonding interface and in the timber piece. An experimental method was developed to verify the theoretical model for bending moment and shear force transfer. Ten short span beam specimens of Pinus radiata D. Don were spliced with bonded-in plates in one end, and they were tested by bending with different anchorage lengths to establish a relationship with load-carrying capacity. Furthermore, the effect of temperature (−20 to 50°C) and moisture content (9–30%) changes were analyzed in two groups of six short beam specimens and in bonding shear test specimens using two different epoxy formulations. The theoretical model predicts conservative values of load-carrying capacity. Temperature and moisture changes cause a reduction of mechanical properties, but to different degrees depending on the epoxy formulation.