Embedding strength of Brazilian woods and recommendation for the Brazilian standard

Abstract

The design of dowelled connections for timber structures based on the Brazilian standard NBR 7190 results in an excessive number of fasteners due to the low value obtained for the wood embedding strength when using the calculation model proposed by the standard. The main objective of this research was to study, experimentally and analytically, the embedding strength of Brazilian reforestation woods according to US and European standards (ASTM D 5764 and EN 1995-1-1:2004) in order to propose a better embedding model for the Brazilian norm for wooden structures. Test specimens were made using Pinus elliottii (softwood) and Eucalyptus saligna (hardwood) and steel fasteners of diameter 6.35 mm. For P. elliottii, the experimental values of embedding strength obtained using D 5764 approached the analytical values. However, for E. saligna, the analytical embedding strengths obtained using D 5764 were higher than the experimental embedding strengths. The model proposed by the European standard proved to be more suitable for obtaining the wood embedding strength. For the European standard, smaller dispersions of data that relate wood density to embedding load were obtained, indicating the better accuracy of the European model.