Timber joints with glued-in FRP rods

Timber joints with glued-in rods constitute a viable solution for numerous structural applications; they are, however, not widely used, partially for a lack of design guidance. These joints, especially when using fibre-reinforced polymers (FRP), have a series of advantages, e.g., the formation of very strong and stiff connections, very high fire resistance, and improved aesthetics. Experimental and numerical investigations were carried out on joints composed of timber and glued in glass FRP rods. A total of 155 specimens with two different timber species, two different adhesives and a variety of different embedment lengths and rod diameters were produced and tested under quasi-static uni-axial tension short term loading. It was found that the strength increased with the overlap length up to an apparent maximum and that capacity is directly correlated to rod diameter. The accompanying numerical simulation indicated that the joint failures were initiated by a combination of local tension perpendicular to the grain and shear parallel to grain stresses. The numerical model was effective in predicting the structural behavior of these joints, suggesting it can be used to develop a numerical based method to predict failure loads.