Effect of temperature on the mechanical performance of glued-in rods in timber structures

Structural bonding technology has proven to be an economically and attractive connection process in timber engineering. Within old or historical wooden buildings, local reinforcement of weak zones is often performed with glued-in rods. This kind of connection typically allows the transfer of loads within wooden elements by means of threaded steel rods glued with a structural adhesive. This paper relates to experimental and numerical investigations on small sized specimens, with the aim of providing a better knowledge about the elastic behavior according to temperature. Experimental results reveal that stiffness of bonded-in rods significantly decreases once the glass transition temperature of the adhesive is reached. However, the ultimate shear strength is constant and sudden failures occur in the wood close to the adhesive whatever the temperature is. Then, an elastic finite element model allows the evolution of the Young modulus of the adhesive with temperature changes and also reveals the stress distribution along the glued-in depth during the elastic regime.