US university researches use of tree forks as structural nodes

12 May 2022

Massachusetts Institute of Technology (MIT) researchers are exploring using discarded tree forks as load-bearing joints in structures.

The research has stemmed from reducing carbon emissions in construction and looking at using more wood.

Caitlin Mueller, an associate professor of architecture and of civil and environmental engineering in the Building Technology Programme at MIT, said the timber industry was currently focused on harvesting straight sections of trees in its aims to produce wooden replacements for traditional concrete and steel elements.

Irregular sections such as knots and forks are often turned into pellets, burned, or mulched.

But over the last few years, Professor Mueller and her digital structures research group have been developing a strategy for “upcycling” those waste as structural components. 

The focus is on tree forks where the trunk or branch of a tree divides in two, forming a Y-shaped piece. 

“Tree forks are naturally engineered structural connections that work as cantilevers in trees, which means that they have the potential to transfer force very efficiently thanks to their internal fibre structure,” she said. 

She and her team have developed a five-step “design-to-fabrication workflow” that combines natural structures such as tree forks with the digital and computational tools now used in architectural design. 

This could also help architects explore new forms in building design.

Researchers have formulated five steps in their design-to-fabrication workflow for making spatial structures using an inventory of tree forks, including a digital library of tree forks, generation of machine codes for fast cutting and assembly instructions.

A structure incorporating tree fork joints was erected temporarily on the MIT campus, featuring 12 nodes. Researchers plan to finish designing and building the complete structure, which will include about 40 nodes.

Research will continue with plans to include working with larger material libraries, some with multibranch forks.

Tree forks are being researched for use as structural timber nodes