Strategies for ductile connections in mid-rise timber buildings in context of a circular economy

Abstract

The use of timber buildings as a CO2-sink has the potential to prolong the sequestration of CO2 from decades to centuries. In Austria, a small percentage of the building construction volume is built of timber, yet 97% of the annual yield forest is already harvested. This proportion necessitates the exploration of novel sources, such as the reuse of mid-rise timber buildings. The reuse of components in a circular economy requires damage-free dismountable components. The predominant brittle fracture characteristics of timber require the design of ductile joints in timber construction. In recent decades, this ductile behaviour has been achieved primarily through shear-stressed connections, i.e. by damaging the structure of timber (embedment strength) or the pin-shaped fastener (incomplete formation of yield joints). Dimensioning in the elastic range leads to dismountable connections, however, with uneconomical results. One solution is new connection systems with interchangeable dissipative elements for capacity design. The analysis confirms the suitability of several connection systems in circular economy for elastic applications. Further research is required in the following areas: the optimisation for ultimate limit state areas, the collection of test data for deviating application scenarios; and the topic of prestressed timber connections. The presentation will focus on an overview of potential strategies for ductile connections in the context of a circular timber economy.