New research at the Massachusetts Institute for Technology (MIT) could help architects and builders reduce the carbon footprint of truss structures.

The analysis by graduate student Ernest Ching and MIT Assistant Professor of Civil and Environmental Engineering Josephine Carstensen appeared in the journal Engineering Structures in November 2021.

The researchers say the materials used in the construction and ongoing operations of buildings, bridges, towers and other structures with diagonal struts contribute extensively to global warming. But little quantitative research has been done on selecting suitable materials for the structure to minimise its contribution to global warming.

The embodied carbon in a construction material includes the fuel used in the material’s production (for mining and smelting steel, for example, or felling and processing trees) and transporting the materials to a site. It also includes the equipment used for the construction itself.

Ching and Carstensen use a topology optimisation technique to create a set of computational tools that could help architects and engineers design legally compliant structures with less embodied carbon.

When the user inputs parameters, such as the amount of load to be supported and the dimensions of the structure, the system produces designs optimised for different characteristics, such as weight, cost, or, in this case, global warming impact. The tool can be applied at any stage of the planning and design process.

Ching and Carstensen reengineered several trusses using their optimisation tools as an exercise. It demonstrated that significant savings in embodied greenhouse gas emissions are achievable with no performance loss. “It’s about choosing materials more smartly for the specifics of a given application.”

The tools are not yet ready for commercial use, and research continues. They believe it will make inroads into the mass timber construction industry and reduce greenhouse gas emissions.

Reference: Ernest Ching, Josephine V. Carstensen. Truss topology optimisation of timber–steel structures for reduced embodied carbon design. Engineering Structures, 2021; 113540 DOI: 10.1016/j.engstruct.2021.113540