Comparison of experimentally obtained and theoretically determined in the Dlubal RFEM 5 software physical and mechanical properties of massive, glued laminated and cross-laminated timber beams

The article presents the results of research and verification of experimentally obtained physical and mechanical characteristics of beams made of massive, glued laminated (glulam) and cross-laminated timber (CLT). The purpose of the study is to compare the real and theoretical deflections of the beams, determined with the Dlubal RFEM 5 finite element analysis software. Previously, experimental studies were conducted to determine the modified deformation modulus (deformation modulus with consideration of influence of shear modulus) for each type of timber beams. The modeling was performed in three stages: using 1D member finite elements, 3D Solid finite elements and a 3D Solid model of the CLT beam considering the orientation of the lamellae fibers in each layer. For each type of timber beam, characteristics were determined for the corresponding material models: isotropic linear-elastic material model for 1D finite elements and orthotropic linear-elastic 3D material model for 3D finite elements. Theoretically calculated deflections were compared with experimentally obtained values, which made it possible to evaluate the accuracy of each model. The results showed high accuracy of modeling for massive and glulam timber beams with an error of up to 2%. For CLT beams, an underestimation of the theoretical deflections for models from 1D and 3D finite elements and an overestimation of theoretical deflections for models from 3D finite elements, taking into account the orientation of the fibers of the lamellae, was noted. The research confirms the expediency of using both simplified and detailed models in the analysis of deformations of timber structures. To increase the accuracy of the calculations, it is recommended to further refine the characteristics of the studied materials, in particular, the dependence between the deformation modulus and the shear modulus, as well as considering complex loading conditions, types of supports, and long-term effects in future studies. It is also advisable to carry out additional experiments to clarify the parameters of strength and stiffness characteristic of various configurations of cross-glued beams.