On plastic development of timber structures based on 3D interactive vector-based graphic statics (VGS)

Rasneur, Sylvain [UCL] Jean-Charles Misson [UCL] Zastavni, Denis [UCL] Jasienski, Jean-Philippe [UCL]

The present contribution addresses both the topics of the design of timber-to-timber joints and the design of innovative and structurally efficient timber structures with the aid of a computational tool based on vector-based graphic statics (VGS). First, this manuscript explains how the latest developments of graphic statics and its use applied to both timber joints and structures can improve the design of structures made of this low embodied carbon material. An exhaustive review of timber assemblies focussing on their sustainability and their structural behaviour is presented. Among these is the notch joint specifically identified in the context of digital fabrication and circular use of timber. Afterwards, the theoretical framework of this research is explained. Taking advantage of the lower bound theorem of the theory of plasticity, the main hypotheses that enable the use of graphic statics and strut-and-tie modelling (STM) for timber are then presented. In addition, the structural behaviour of the single notch joint is evaluated using algebraic dimensioning method. The limitations of this method are pointed out and the article proposes an integrated universal approach to investigate the problem using Strut and Tie Modelling (STM) and stress fields. The results of this theoretical framework are validated trough 1/1 scale lab tests. Finally, the third chapter illustrates the potential of VGS via a Research-by-Design approach. In the aim of testing if designing simultaneously creative and efficient timber structures could be effective while using the VGS, architectural engineering student were asked to focus on both the primary load-bearing structure and the joint- systems.