An experimental comparison of strengthening solutions for dowel-type wood connections

This paper presents an experimental investigation of the development of adhesively bonded reinforcing techniques for dowel-type wood connections. One of the proposed techniques is based on the application of carbon fiber reinforced plastic (CFRP) laminates (glued with epoxy adhesives) in the areas surrounding the holes of the wood members. The other technique is based on a novel reinforcing procedure involving the application of steel inserts that are glued to the holes of the timber members. For this latter technique, two distinct commercial epoxy adhesives were investigated. Both techniques were demonstrated for maritime pine wood. The experimental program comprised embedding tests, carried out according to the procedures of the EN 383 standard, with and without reinforcements, and included both parallel- and perpendicular-to-grain quasi-static loading. The embedding strength and foundation modulus were determined and compared between the non-reinforced and reinforced solutions. Furthermore, three series of single dowel T-connections were tested, one without reinforcement and two series reinforced with metallic inserts and CFRP laminates, respectively. The analysis of the experimental results showed the improved performance of the strengthening solutions. Additionally, it is important to emphasize that the reinforcement based on CFRP laminates was more effective in eliminating brittle failure modes in the wood members.