Glued laminated Robinia hardwood timber for structural use

Robinia wood has a high technical and economic potential due to its future availability, its mechanical properties, and its durability. This also applies to its use in structural timber construction. Such applications require the manufacture of bonded construction products from this type of wood in order to compensate for dimensional shortcomings. In an application-oriented research project, tests were carried out for manufacturing technologies and resulting properties of glued laminated timber made from the hardwood species Robinia for structural purposes. Based on adapted visual grading rules, the strength and stiffness profiles of Robinia laminations were evaluated. The influence of different adhesive types and of production parameters on the strength and durability properties of glued finger joints and glulam bond-lines were characterised. By means of a simulation model based on X-FEM methods in combination with Monte Carlo simulations, the property potential of glued Robinia laminated timber was calculated. The model was calibrated by means of input parameters from the empirical lamination and finger joint test data and verified by a small series of full-scale glulam tests. The investigations showed the great potential of Robinia glulam, especially in highly loaded and heavily weathered applications.