Thermal Shelter for Fossilized Stumps

The Petrified Tree Stumps (PTSs) at the Florissant Fossil Beds National Mon-ument in Colorado are an important part of the ecosystem as they allow the study of prehistoric ecosystems and climates. However, since PTSs erode from environmental factors such as free-thaw cycles, their conservation is of high impor-tance. To assist with the conservation effort, a pavilion prototype was designed and fabricated to demonstrate a potential solution for protecting the stumps, with sensors installed to evaluate the prototype’s thermal performance. Using form-force diagrams from Polyhedral Graphic Statics (PGS), a polyhedral funnel shell pavilion was designed to 1) shield the PTS from environmental conditions and 2) maintain visibility to visitors, as the PTS are public sites. The shell is a timber, open polyhedral lattice with an ethylene tetrafluoroethylene (ETFE) foil enclosure. ETFE provides protection and transparency, meeting objectives and constraints set by the park. An Application Programming Interface (API) was developed to automate the transfer of milling data from the PGS model to the robot for machining. Aluminum channels supporting the ETFE were simi-larly mitered, and an articulated structural connection was developed to affix the enclosure to the shell. On-site construction was assisted with digital twin models created from photogrammetry and laser surveying, allowing for in-situ changes. The design and fabrication workflow, as well as the general requirements and constraints from fabricators and conservationists are discussed. The thermal data collected indicated that the number of freeze-thaw cycles were reduced in the Fall and Spring seasons.

Keywords: timber pavilion, conservation, digital twin, timber construction, robotic prefabrication, ETFE, polyhedral graphic statics