Effect of connection elements on shear strength of wooden pieces for structural use

The mechanical behavior of wood joined by connecting elements under shear stress is not fully understood. This study evaluated the shear strength of wooden pieces connected by nails or screws, with and without adhesive. Each push-out specimen was formed by joining three prismatic wood pieces using connecting elements, with or without adhesive. A total of 60 specimens were produced from 180 prismatic pieces, each measuring 25 mm x 25 mm x 100 mm, of young Eucalyptus wood. In the glued specimens, adhesive was applied on the radial surface of the wood pieces, resulting in a critical section area of 37.5 mm². The results showed significant variations in shear strength between different treatments. Specimens connected only with screws or nails exhibited lower maximum strength compared to glued specimens but demonstrated more ductile behavior. The application of adhesive between the parts increased both strength and stiffness, while the metal pins did not contribute significantly. Furthermore, applying screws or nails immediately after the adhesive reduced the shear strength of glued pieces by 24% and 39%, respectively, according to push-out tests.