Efeito dos elementos de ligação na resistência ao cisalhamento em peças de madeira de Eucalyptus para uso estrutural

Abstract

The mechanical behavior of wood joined by connecting elements when subjected to shear stress is not yet well established. Thus, the present study aimed to evaluate the shear strength in wooden pieces connected by nails or screws with and without adhesive. For this, 60 specimens were made for the push-out test, from three prismatic pieces of 25 x 25 x 100 mm (Radial x Tangential x Longitudinal) with Eucalyptus wood. The pieces were connected by connecting elements with and without application of 250g / m² polyvinyl acetate adhesive, totaling six treatments, so that the critical section planes parallel to the radial direction of the wood and had an area of 37.5 mm². From this, the results showed that the shear strength varied complementarily between treatments. The tests were only screwed and the nailed bodies resisted lower values of maximum strength in relation to the treatments that received glue, however, it causes a more ductile behavior. An application of glue between the parts increases the strength of the element, but the metal pins have made no contribution. Also, the application of screws or nails immediately after applying the label did not improve the mechanical performance of the parts, causing a reduction of 24% and 39%, respectively, in shear strength in a push-out test. The metallic pins of the treatments that received glue not forming, a failure of the element originating in the glue line. While, the treatments that received only nails or screws, the pins exhibited a type II formation mode according to Johansen's theory, with the formation of a plastic kneecap.