Abstract
ABSTRACT The objectives of this study were to evaluate the relationship between the density and the EW (modulus of elasticity) values obtained by two non-destructive methods: the accuracy of an expeditious method using a graduated ruler; and the homogenization of elasticity between the methods for glulam elements. In the analysis, displacements were measured with a graduated ruler and an automatic data acquisition system of 136 glulam pieces with corresponding structural size was used. The methods were evaluated by correlations, and the homogenization of elasticity was evaluated by the Tukey test. We found that density does not influence the EW values obtained by the studied methods, and it is concluded that an expeditious method using a graduated ruler can be used to determine EW by applying a corrected equation.
Highlights
Glued laminated timber (Glulam) is an engineered product that demands precision at all stages of the production process, given its use in construction for long periods of time, and must be resistant to stresses with the least possible deformation (Segundinho et al, 2013)
Due to the heterogeneity of the batch caused by the different ages and supply, the laminated pieces were distributed by apparent density, determined by the ratio between the individual mass obtained by a digital scale, and the volume measured with a digital caliper and measuring tape, according to Annex B of NBR 7190 (ABNT, 1997)
In order to randomize the distribution of density classes, the frequency distribution procedures were implemented according to the Sturges rule (Correa, 2003), resulting in 8 classes with the following ranges: Class 1 (C1) = 270 to 300 kg.m–3; Class 2 (C2) = 300.1 to 330 kg.m–3; Class 3 (C3) = 330.1 to 360 kg.m–3; Class 4 (C4) = 360.1 to 390 kg.m–3; Class 5 (C5) = 390.1 to 420 kg.m–3; Class 6 (C6) = 420.1 to 450 kg.m–3; Class 7 (C7) = 450.1 to 480 kg.m–3; Class 8 (C8) = 480.1 to 510 kg.m–3
Summary
Glued laminated timber (Glulam) is an engineered product that demands precision at all stages of the production process, given its use in construction for long periods of time, and must be resistant to stresses with the least possible deformation (Segundinho et al, 2013). Glulam requires quality control during its production to ensure that its physical and mechanical properties are adequate to the requirements of projects and standards. For the best use and quality of glulam material it is necessary to know the physical and mechanical properties of the laminated wood pieces that will compose the glulam. In the manufacturing process it is often not possible to obtain material of the same origin, and there may be a lot of wood pieces with different densities and/or ages among the glulam timber. It is necessary to make the separation by density, creating new lots with more homogeneous properties. It is possible to estimate the mechanical properties of a new batch of wood based on the direct relation between its density and the mechanical characteristics of the same species (Armstrong et al, 1984; Bodig & Jayne, 1993; Dias & Lahr, 2004; Lobão et al, 2004)
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