Resumo A NBR 7190:1997 "Projeto de Estruturas de Madeira" fornece os procedimentos para vários ensaios mecânicos, entre eles, o ensaio de Flexão estática para determinação de Módulo de Elasticidade (Em) e Valor Convencional de Resistência (fm). É comum a caracterização de lotes de madeira com resumido número de corpos de prova, o que torna dificultosa a realização do teste de estimativa da ruptura, e depois disso, proceder o ciclo de carregamento para estimativa de Em. Nestes casos, parâmetros de Deflexão ao invés de parâmetros de Força são utilizados para o ciclo de carregamento. Este trabalho objetiva identificar um padrão entre parâmetros de Força e Deflexão investigando a curva Força vs. Deflexão do ensaio de flexão estática em corpos de prova de madeira. De acordo com os resultados, existe um padrão pronunciado entre parâmetros de Força e Deflexão na região linear da curva Força vs. Deflexão, e baseando-se nisto, um modelo de regressão linear foi proposto envolvendo os logarítmos da porcentagem de força (em relação à ruptura) e o denominador do valor do vão (como sendo um parâmetro de deflexão), resultando R2 igual a 97,41%. Este resultado torna mais fácil a realização de ensaios de flexão estática em laboratórios especializados em ensaios em madeira.

Abstract The NBR 7190:1997 "Design of Timber Structures" provides the procedure for several mechanical tests, and among them, the Static bending test for Modulus of Elasticity (Em) and Conventional Value of Strength (fm) determinations. It is common to characterize wood batches with a small number of specimens, what makes it difficult to perform an estimative test for rupture determination, and afterwards, to carry out the loading cycle for Em estimation. In these cases, instead of Force parameters, Deflection parameters are used for the loading cycle. This paper aims to identify a pattern between Force and Deflection parameters by investigating the Force vs. Deflection curve of the static bending test of wood specimens. According to results, there is a well pronounced pattern between Force and Deflection parameters in the linear part of the Force vs. Deflection curve, and based on this, we proposed a linear regression model between logarithm values of the force percentage (in relation to the rupture) and the denominator of the span value (as a Deflection parameter), resulting R2 equal to 97.41%. This result makes the conduction of the static bending test easier in specialized laboratories for testing of wood.

ABSTRACT The CLT is a building material that comes mainly used in Europe where it was developed. Lightweight, sturdy and eco-friendly, this material has become one of the most important constructive methods in the world. CLT are panels formed by layers of wood glued to each other orthogonally, always in odd numbers, symmetrical with respect to the central layer. The dimensions can vary from 50 to 500 mm in thickness, and depend on the application, which can be a slab or wall element, the width and length are adjustable, being able to produce up to 20 meters in length. This work presents tests and results obtained in two types of CLT panels produced in a laboratory. One panel made with Pinus taeda and MUF (melamine urea formaldehyde) adhesive and other one made Eucalyptus urograndis with PU (polyurethane) adhesive. The objective was to evaluate the stiffness and to through the analytical method using the Analytical Design Method (γ-method), and through experimental tests in the laboratory, comparing the values obtained in each method. In the experimental test, the Eucalyptus panel obtained better strength and stiffness than Pinus panel, and in analytical calculation using the Analytical Design Method (γ-method), obtained Elastic Modulus (MOE) values slightly above experimental values, and stiffness values (EI) considerably below experimental values. Concluded that the Cross Laminated Timber produced with Pinus and Eucalyptus planted in Brazil obtained resistance and stiffness considered suitable for structural use and showed that it could be a new alternative of constructive material to be used in the country.

ABSTRACT The CLT is a building material that comes mainly used in Europe where it was developed. Lightweight, sturdy and eco-friendly, this material has become one of the most important constructive methods in the world. CLT are panels formed by layers of wood glued to each other orthogonally, always in odd numbers, symmetrical with respect to the central layer. The dimensions can vary from 50 to 500 mm in thickness, and depend on the application, which can be a slab or wall element, the width and length are adjustable, being able to produce up to 20 meters in length. This work presents tests and results obtained in two types of CLT panels produced in a laboratory. One panel made with Pinus taeda and MUF (melamine urea formaldehyde) adhesive and other one made Eucalyptus urograndis with PU (polyurethane) adhesive. The objective was to evaluate the stiffness and to through the analytical method using the Analytical Design Method (γ-method), and through experimental tests in the laboratory, comparing the values obtained in each method. In the experimental test, the Eucalyptus panel obtained better strength and stiffness than Pinus panel, and in analytical calculation using the Analytical Design Method (γ-method), obtained Elastic Modulus (MOE) values slightly above experimental values, and stiffness values (EI) considerably below experimental values. Concluded that the Cross Laminated Timber produced with Pinus and Eucalyptus planted in Brazil obtained resistance and stiffness considered suitable for structural use and showed that it could be a new alternative of constructive material to be used in the country.

Created in the 1940s, the splice finger-joint type for wood has now been more used to compose structural materials wood base as Glued Laminated Timber (Glulam) and Cross Laminated Timber (CLT). The main advantage of this amendment is to provide a simple and economical way to join timber parts on segments. This study evaluated by means of tensile tests the capacity of this type of joint (structural dimension of 21mm) to bond together Lyptus® wood beams (a Eucalyptus grandis and Eucalyptus urophyla hybrid) using Jowat polyurethane glue (Model 680.20) as compared to similar seamless beams. The results indicate that the seamless beams are 47.72% more resistant to traction (in characteristic values) than those with finger joints. However, to form structural elements where there is redundancy overlapping parts, such as Glulam and CLT, the values obtained can be considered satisfactory. Also noted is that denser samples have better traction results due to better bonding of the densest parts. The use of finger-joint and polyurethane adhesive o bond hybrid eucalyptus, although more brittle than wood without seams, enable the use of shorter wood sections for the composition of major structural elements, optimizing better forest material.