Effect of nondestructive testing of laminations on the bending properties of glulam beams made from louro-vermelho (Sextonia rubra)

Abstract

This work aims to assess the bending properties of glued laminated timber beams (glulam) manufactured with species louro-vermelho (Sextonia rubra). Laminations were nondestructively tested using the transverse vibration method (E Mlam ). Then 10 glulam beams were manufactured and tested in static bending according to ASTM D 198 standard, having modulus of elasticity (E M ), modulus of rupture (f M ), and bending moment (M) determined. The finished beams were also tested by the transverse vibration method (E Mvt ). It was noted that the E Mvt value was only 2% lower than the E M value. Using laminations with a high modulus of elasticity did allow effective gain in stiffness. Therefore, results indicate that the transverse vibration method is a valid, reliable technique both for testing glulam laminations and for assessing stiffness in finished beams. Bending properties in glulam beams were influenced by the stiffness of constituent laminations.Key words: Transverse vibration, glued laminated timber, static bending. EFEITO DA CLASSIFICAÇÃO NÃO DESTRUTIVA DAS LÂMINAS SOBRE AS PROPRIEDADES DE FLEXÃO DE VIGAS MLC PRODUZIDAS COM LOURO-VERMELHO (Sextonia rubra) RESUMO: Conduziu-se este trabalho, com o objetivo de avaliar as propriedades de flexão de vigas de madeira laminada colada (MLC) produzidas com a espécie louro-vermelho (Sextonia rubra). As lâminas foram classificadas não destrutivamente pelo método de vibração transversal (E Mlam ). Em seguida, 10 vigas de MLC foram produzidas e ensaiadas em flexão estática, conforme a norma ASTM D 198 e determinados o módulo de elasticidade (E M ), o módulo de ruptura (f M ), e o momento fletor (M). As vigas consolidadas foram ainda avaliadas pelo método de vibração transversal (E Mvt

Effect of Nondestructive Evaluation of Veneers on the Properties of Laminated Veneer Lumber (LVL) from a Tropical Species

“…On the other hand, the values of dynamic modulus of elasticity observed for boards were higher compared to veneers. [12], who employed the transverse vibration nondestructive method to grade lumber to produce glulam beams. The mechanical properties of the LVL boards are presented on Table 2.…”

“…Visual and acoustic nondestructive methods have been used previously to sort logs, lumber and veneers employed in the manufacturing of ply-based wood composites, as seen in several works [10][11][12][13][14][15]. Wang et al [15], while studying ultrasonically (US) rated veneer from red maple, found a positive relationship between veneer US variables and LVL billet stiffness and strength.…”

“…Bortoletto [13] on the other hand did not find any effect on the properties when plywood was manufactured using randomly or ultrasonically rated veneers from Pinus merkusii. Teles et al [12] found that lumber nondestructively tested by means of transverse vibration yielded stronger and stiffer glulam beams made from a tropical hardwood (Sextonia rubra).…”

Theoretical and experimental deflections of glued laminated timber beams made from a tropical hardwood

“…The feasibility of assembling glulam beam from the well-known Brazilian Amazonian hardwood louro-vermelho (Sextonia rubra) was demonstrated in our previous study (Teles et al 2010). According to the results, the glulam beam presented the following flexural properties: modulus of elasticity, :15800 N/mm 2 ; modulus of rupture, :64 N/mm 2 ; and rupture load, :14600 N. Louro-vermelho is widely used in light construction and often found in the Northern states of Brazil.…”

“…After load reached 4000 N, the deflection measurement device was removed and the beam tested up to rupture. Further details on glulam beams assembling and testing can be found in Teles et al (2010).…”