Modification factors of the embedding strength dependent on the temperature and load-to-grain angle for two wood species planted in Brazil

Abstract

This research aims to assess the influence of the temperature and the load-to-grain angle on the embedding strength of the timber of the two most used wood species in Brazil, proposing a continuous function that describes the behaviour of the embedding strength, which can be used in advanced numerical models for estimating the load-bearing capacity of the bolted connections. Embedding tests were carried out with 1400 specimens made according to ASTM D 5764-97a. The experimental program consists of 10 temperature levels and 7 load-to-grain angles for each Pinus elliottii Engelm and Eucalyptus saligna Sm samples. For each combination of one temperature level and one load-to-grain angle, ten specimens were used. The moisture content, density, mean and characteristic embedding strength and modification factor of the characteristic embedding strength were determined. The embedding strength decreases with the increase of the load-to-grain angle and significant differences occur between mean embedding strengths at room temperature (25 °C) and those at elevated temperatures. A fitted model of the modification factor of the characteristic embedding strength was determined for both species. The adjusted coefficients of determination of the models are 0.87 and 0.92 to the Pinus elliottii and Eucalyptus saligna, respectively. These models are continuous functions that can be useful for predicting bolted connections load capacity in advanced numerical models in situations of temperature and load-to-grain angles similar to the ones in this research. They should be used with caution since they present a large variability in their results.