Structural Performance of Glulam Beams Improved by Composing the Cross-Section with Lamellae of Different Strength Classes

Glued laminated timber (glulam) is a high-performance structural wood product. However, means are still being researched to increase efficiency in challenges with a large scale of complexity, either owing to the diversity of the lamella’s material properties or through the development of computational models to better represent the real behavior of the material. This study aimed to determine a more efficient combined glulam beam in terms of the lamella’s proportion. The beams with a 12,000 mm span and a 150 × 600 mm cross-section were modeled using solid finite elements and a linear-elastic isotropic model. Two homogeneous and four combined glulam cross-sectional compositions were established based on the physical and mechanical properties of two strength classes (35 and 50 MPa), and their deflections and bending stresses were evaluated. Compared with that of homogeneous glulam beams with lamellae of the strength class 35 MPa, for softwood and hardwood lamellas, the combined cross-section with 33.3% of the lamellas of class strength 50 MPa, the load corresponding to the deflection limit increased by 17% and 12.4%, respectively. This composition had a higher self-weight only in relation to homogeneous glulam. It can be concluded that the combined glulam with a proportion of 33.3% was more efficient, considering the behavior of the beam under a load corresponding to the deflection limit, and that the lower self-weight affects the production and transportation processes.