Mechanical properties of Glued-laminated timber made up of mixed tropical wood species

This paper deals with an innovative experimental study performed on glued-laminated timber (GLT) beams, machined and made with three tropical hardwood species. Defect-free beams were obtained by combining alternatively the lamellas taken from the densest to the least dense species, to have TRIO and DUO specimens. Then, static 3-point bending tests were performed on these beams, to assess their mechanical properties and their reliability. Finally, the shear strength tests of the various glue joints are done to understand the failure mode of the beams observed during the bending tests and their impact on the mechanical behaviour of the GLT beams tested. The results show for the two types of GLT (DUO and TRIO's beams) studied here that: (i) comparatively to the combinations of two lamellas (DUO's beams), by taking into account the solid woods and homogeneous beams as references, beams with three lamella combinations (TRIO's beams) present the best mechanical characteristics; (ii) There is a significant influence of the individual lamella's position or the type of lamella on the global behaviour of the GLT's beams. Moreover, the advantages of this type of timber beam material are investigated and shown herein.