The use of cross-laminated timber (CLT or XLAM) in the multi-storey buildings construction sector has been spreading in Europe and North America over the last twenty years. Considering that Chile has one of the largest radiata pine forest resources of the world, it is clearly possible to introduce this timber construction system in Chile. Therefore the mechanical characterization and seismic behaviour of 3-ply cross-laminated timber panels made of Chilean radiata pine were studied. The panels (2.5 m high, 1.2 m wide and 0.12 m thick) were manufactured in the Materials Research Laboratory of the Civil Engineering Department at the Universidad de Santiago de Chile (LIMUSUSACH) in accordance with the current Chilean standards, which are based on ASTM standards. The New Zealand standard (BRANZ P21) for cyclic tests was also applied. These panels are intended to be used for the design of earthquake-resistant systems in mid-rise buildings.
In this paper we investigate the rolling shear failure in cross-laminated timber structures by homogenisation and cohesive zone models. In order to predict the structural response, four spatial scales are interlinked within a purely kinematic multi-scale modelling framework. The constitutive description has incorporated information coming from the wood cell-wall in the order of a few nanometres, wood fibres with dimensions of tens of micrometres and growth rings described by a few millimetres. The computational homogenisation scheme is solved sequentially from the lowest to the highest level in order to determine the effective mechanical properties for the fourth (structural) scale represented by a cross-laminated timber plate with dimensions of the order of one meter. In order to simulate the cracking in the material, a cohesive zone model is adopted at the homogenised macroscopic scale. The finite element problem is then solved using a mixed domain decomposition strategy due to its huge number of unknowns. This approach allows us to capture interlaminar and inter-fibre cracking and to solve the macroscopic equilibrium problem using parallel computations. Our numerical predictions are compared with experimental results and are validated successfully. In particular, we study the influence of wood density, edge-gluing and span-to-depth ratio on the rolling shear failure in cross-laminated timber.
In this work, a numerical-experimental approach is used to study the elastic buckling of CLT panels. First, a finite element-based multi-scale model is developed to study the linear elastic buckling behaviour of CLT panels. The model incorporates wood’s most relevant microstructural features, such as the volume fraction of hemicellulose, lignin and cellulose, their mechanical and physical properties, microfibril angle, etc.; which are crucial to capture the inherent orthotropic nature of wood observed at the macroscopic level. Furthermore, the values of key microstructural parameters are determined through a parameter identification procedure, in which experimentally measured values of density and longitudinal Young’s modulus of radiata pine grown in Chile are used as target values. The model is successfully validated with results from buckling tests performed on CLT panels’ specimens with different thickness and slenderness ratios. The validation clearly shows the capability of the model to predict the buckling response of CLT panels. Finally, the model is used illustrate how parameters such as wood density and panel number of layers influence the buckling response of CLT panels.
In this paper we investigate the damage process in cross-laminated timber (CLT) structures by a computational homogenisation approach enriched with cohesive zone models. In order to predict the undamaged structural response, four spatial scales are interlinked within a multi-scale finite element modelling scheme. To simulate the cracking process in the material, a cohesive zone model (CZM) is adopted at the homogenised macroscopic scale. This double approach allows us to model successfully the progressive damage process in CLT plates subject to threepoint bending.