Influence of orientation and number of layers on the elastic response and failure modes on CLT floors: modeling and parameter studies

Franzoni, Lorenzo; Lebée, Arthur; Lyon, Florent; Forêt, Gilles

doi:10.1007/s00107-016-1038-x

Cited by 28 publications

(24 citation statements)

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“…This may explain some discrepancies in addition to wood natural variability. Franzoni et al (2016a) and Perret et al (2018) Franzoni et al (2016a) performed double lap shear tests on a small batch of CLT boards whose typical cross section is given in Figure 1 As already noted in Section 3, G C Z may be up to 2.5 times larger than the local rolling shear modulus G RT . In addition, for 30°< α < 60°, the closed-form bounds G R C Z and G V C Z can be well approximated by direct averages G S N N and G C N N derived in Section 2.1.…”

Section: Comparison With Experimental Datamentioning

confidence: 95%

“…In the CLT-designer software, Thiel and Schickhofer (2010) suggest to use Timoshenko beam theory and derived the shear stiffness of CLT beams from the Jourawski method. Advanced models have also been suggested by Franzoni et al (2016b) for the bending of CLT panels and by Perret et al (2016) for the buckling of CLT panels. In these methods, it is assumed that the mechanical behavior of each layer, composed of several boards, can be modeled as homogeneous.…”

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confidence: 99%

“…Because of the high stiffness contrast between E L and E C , the cross Young's modulus E C is often neglected (Thiel and Schickhofer, 2010). Moreover, because of the thickness of CLT and of the cross layers, the out-of-plane shear stiffness of CLT, composed of the longitudinal shear stiffness modulus G LZ and of the cross-layer shear stiffness modulus G C Z , is also involved in the bending (Franzoni et al, 2016b) and the buckling behavior of CLT (Perret et al, 2016). In the γ-method -detailed in (Gagnon and Pirvu, 2013)-G LZ is neglected because of the stiffness contrast compared to G C Z .…”

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confidence: 99%

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Equivalent stiffness of timber used in CLT: closed-form estimates and numerical validation

et al. 2019

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In this paper, a closed-form approach is presented to estimate rapidly the equivalent stiffness of boards used in Cross Laminated Timber (CLT) panels from local orthotropic behavior at ring scale for varying sawing patterns.It is first assumed that narrow edges are glued. In this case, closed-form Reuss and Voigt bounds are derived for the equivalent layer behavior of CLT. An application to Norway spruce boards is presented and reveals that the cross-layer (rolling) shear behavior lies between 100 and 150 MPa with a careful selection of the board sawing pattern. Then, using finite element method, upper bounds for the cross-layer shear stiffness modulus of boards with and without glued edges are calculated and theoretical predictions are compared with recommendations and experimental data from the literature.Finally, it appears that these bounds remain relevant for CLT layer with unglued narrow edges for common aspect ratios.

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Equivalent stiffness of timber used in CLT: closed-form estimates and numerical validation

et al. 2019

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“…CLT panels are classically used in walls, floors and roofs as load carrying plate elements. Thus, several studies were performed to model the bending of CLT plates ( Franzoni et al, 2015( Franzoni et al, , 2016Guggenberger and Moosbrugger, 2006;Stürzenbecher et al, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

The Bending–Gradient theory for the linear buckling of thick plates: Application to Cross Laminated Timber panels

Perret

Lebée

Douthe

et al. 2016

International Journal of Solids and Structures

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a b s t r a c tIn this paper, the linear buckling of a heterogeneous thick plate is studied using the Bending-Gradient theory which is an extension of the Reissner-Mindlin plate theory to the case of heterogeneous plates. Reference results are taken from a 3D numerical analysis using finite-elements and applied to Cross Laminated Timber panels which are thick and highly anisotropic laminates. First, it is shown that critical buckling loads are close to the material failure load which proves the necessity of a design model for the buckling of Cross Laminated Timber panels. Second, the soft simple support boundary condition is introduced as an opposition to the conventional hard simple support condition. It is shown that this distinction could be taken into account for designing timber structures depending on the accuracy needed. Third, it is observed that for varying plate geometries and arrangements, the Bending-Gradient theory predicts more precisely the critical load of CLT panels than classical lamination and first-order shear deformation theories. Finally, it is demonstrated that one of the suggested projections of the BendingGradient on a Reissner-Mindlin model gives very accurate results and could favorably allow the development of engineering recommendations for estimating properly transverse shear effects.

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“…Outro método proposto foi o k-method conforme Blass e Fellmoser [7]. Segundo Franzoni et al [8] estes são os três principais méto-dos de cálculo das estruturas de CLT utilizadas como placas de cobertura ou de piso sujeitos a esforços de flexão.…”

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A madeira laminada cruzada: aspectos tecnológicos, construtivos e de dimensionamento

Amorim

Carrasco

2018

Matéria (Rio J.)

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RESUMOOs painéis de madeira laminada cruzada (CLT) são formados por lâminas de madeira com grandes dimensões arranjadas ortogonalmente e unidas com adesivo estrutural sob alta pressão. O sistema de laminação cruzada possibilita ao CLT trabalhar como um elemento estrutural rígido e autoportante. Além disso, são isolantes térmicos e acústicos e apresentam bom comportamento para situações de incêndio. São utilizados como elementos estruturais e de fechamento em edificações de vários pavimentos em construções pré-fabricadas e este sistema construtivo pode ser considerado mais sustentável, que gera menos impactos ao meio ambiente, frente às soluções tradicionais brasileiras. A madeira é um recurso natural renovável e quando utilizada na construção, cumpre um papel importante para o meio ambiente: armazenar o CO 2 e utilizar baixa energia para sua manufatura e aplicação quando comparada aos materiais convencionais empregados na construção como o aço, o concreto e o alumínio. Para o dimensionamento dessas estruturas ainda não existe uma abordagem de cálculo universalmente aceita pelos projetistas e fabricantes de CLT. Neste trabalho, são dimensionados os painéis de CLT do tipo lajes de piso ou cobertura sujeitos à flexão a partir dos principais métodos de dimensionamento. Os resultados obtidos foram comparados e constatou-se que o mé-todo de maior precisão foi o que considerou a rigidez estrutural de todas as lâminas. A maior precisão no projeto e dimensionamento dos painéis de CLT contribui para uma engenharia sustentável, na medida em que otimiza o uso do material na estrutura. Palavras-chave: Madeira laminada cruzada, sistemas construtivos, sustentabilidade. ABSTRACTCross laminated timber panels (CLT) are formed by large-sized orthogonally arranged wood layers bonded with structural adhesive under high pressure. The cross-lamination system provides to the CLT to work as a rigid and self-supporting structural element. In addition, they are thermal and acoustic insulation and have a good resistance in fire situations. They are used as structural and closing elements in multi-floor constructions and this constructive system can be considered more sustainable, which generates less impact to the environment, compared to traditional Brazilian solutions. Wood is a renewable natural resource and when used in construction it plays an important role for the environment: storing CO 2 and using low energy for its manufacture and application when compared to conventional materials used in construction such as steel, concrete and aluminum. In these structures design there is still no universally accepted analytic approach by CLT designers and manufacturers. In this work, the CLT panels used as floor or roof slabs subject to bending are dimensioned the most important methods used. The results were compared and it was concluded that the more accurate methods consider the rigidity and structural resistance of all layers. Greater precision in the designing of the CLT panels contributes to sustainable engineering as it optimizes the u...

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Influence of orientation and number of layers on the elastic response and failure modes on CLT floors: modeling and parameter studies

Cited by 28 publications

References 19 publications

Equivalent stiffness of timber used in CLT: closed-form estimates and numerical validation

Equivalent stiffness of timber used in CLT: closed-form estimates and numerical validation

The Bending–Gradient theory for the linear buckling of thick plates: Application to Cross Laminated Timber panels

A madeira laminada cruzada: aspectos tecnológicos, construtivos e de dimensionamento

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