Resistência ao arrancamento de pregos em madeira de Brachystegia Spiciformis e Julbernadia Globiflora

Abstract

The aim of this study was to evaluate the resistance to nail pullout in wood from the species Brachystegia spiciformis and Julbernardia globiflora and pine Pinus taeda for structural purposes. The test procedures were based on the ASTM D 1761-2012 standard. Twenty specimens of each species with dimensions of 5x5x15cm were used, of which 10 were subjected to the insertion of nails of 3.6mm in diameter and another 10 to nails of 4.7mm in diameter. The samples were acclimatized to a temperature of 20ºC and a humidity of 65% until reaching a humidity of 14±1%. They were then subjected to the insertion of two nails in each anatomical plane and then to a nail pullout test in a universal machine for testing the mechanical resistance of materials. The results indicate that the nail pullout resistance values ​​ranged from 1053.46 to 4406.78 N for the messassas and from 1315.00 to 2566 for the pine, depending on the nail diameter and the anatomical plane considered. For the 3.6 mm nail, Pinus taeda showed greater pullout resistance than Brachystegia spiciformis. As for the 4.7 mm nail, no statistically significant differences were observed between Brachystegia spiciformis and Pinus taeda. In turn, Julbernardia globiflora showed pullout resistance values ​​with statistically significant differences and greater than those of Pinus taeda. No statistically significant differences were observed between the tangential and radial planes; only the transverse plane showed statistically significant differences in all species as well as nail diameters. The study concludes that of the three species, J. globiflora has the greatest potential for application in joints with nails where greater resistance to nail pullout is required, as is the case with wooden ceiling structures in infrastructures resilient to the effects of climate change.