Structural Timber & Connections

Timber is a widely available natural resource that can be used as a valuable and sustainable material for construction. As a structural material, however, it is highly complex. This research area focuses on the development of fundamental knowledge and calculation models for an improved design of structural timber members and connections. The research includes experimental and numerical analysis of glued-laminated and cross-laminated timber members, as well as connections, aiming at improving the reliability of the mechanical properties and the design models. In addition to strength and stiffness properties, particular attention is given to the behaviour of structural timber members and connections with regard to ductility. Some highlights of concluded research projects are:

• Probabilistic model for the load-bearing capacity of glued laminated timber 
• Improved design model for glued laminated timber beams with unreinforced and reinforced notches
• Strain-based calculation model for centrically and eccentrically loaded timber columns
• Analytical model for the resistance and deformation capacity of fibre reinforced glulam beams
• Design rules for glued laminated timber made of European beech wood
• Improved design models for dowelled and screwed connections, and connections with glued-in rods

Despite the progress in timber engineering, further research is required to make use of the full potential of timber, in particular for larger and tall buildings. The current design of timber structures is based on an element-by-element approach, mostly for the sake of simplicity and due to a lack of fundamental knowledge, in particular about the global behaviour of connections and members. Thus, future basic research priorities include the development of a framework for system-based and performance-based design of timber structures, which will be used for the development of design rules for robust tall timber buildings. In this respect, the structural behaviour and reliability of connections play a fundamental role. Another future basic research area is the combination of different timber species; one reason being the changes expected in the forests due to climate changes. The long-term objective is to assure the availability and the further use of timber as a high quality building material.