Pull-out strength of glued-in GFRP rods in timber connections by using of epoxy resin reinforced by nanoparticles

ABSTRACT Background: In timber structures, connections are the most important and critical section which supply the strength of each structural element. The aim of this study was evaluation the behavior of epoxy resin reinforced by nanoclay (at three levels) on the pull-out strength of glued-in GFRP rods in glulam. For this purpose, two rods with three lengths (50, 150 and 250 mm) and diameters (6.4, 12.7 and 19.1 mm) were inserted at two opposite sides of glulam blocks (with dimension of 8.89 x 8.89 x 29.94 cm) which were glued by epoxy resin. Samples underwent tensile testing and their tensile strength and shear strength were measured. The obtained data were analyzed statistically and the effects of studied factors on bond strength were evaluated. Results: The results showed that the strength of bonding increased with the addition of a low amount of nanoclay, and the length of the rod had a greater effect than its diameter. Furthermore, the amount of nanoclay, rod length and diameter could not significantly affect simultaneously, the performance and strength of glued-in GFRP rods. Conclusion: Nanoclay particle can be considered as a reinforcement for epoxy resin in glued-in GFRP rods and its effect may cause a considerable increase in the mechanical strengths of joints.