April 2015, Northern Minn. – Located 40 miles north of Grand Rapids is the SPRUCE experiment. This project aims to observe varying temperature increases and their effects on Spruce trees and other elements within a bog’s habitat. The Oak Ridge National Laboratory compiled a team, including the structural engineers at Krech, O’Brien, Mueller and Associates, Inc. (KOMA) to bring the experiment to life.
Oak Ridge National Laboratory conducts basic and applied research in order to deliver solutions to problems in energy and security. Under their Climate Change Program, they founded the SPRUCE project. This project consists of 8 octagonal greenhouses built in the Marcell Experimental Forest. Each greenhouse has a mechanical unit which allows warm air to be circulated into the space and control water levels. This allows the laboratory a more defined look at how climate change affects this vulnerable ecosystem and allows them to compare the spruce within the greenhouses with the environment just outside them.
The team consists of greenhouse manufacture Albert J. Lauer, Architectural Resources Inc, Northland Consulting and KOMA. KOMA was responsible for the aluminum design of the greenhouse. The octagonal greenhouses are 28’ tall and 42’ across with a frustum at the top. The pieces were manufactured by Albert J. Lauer in their Farmington shops and shipped to the site. The aluminum pieces were then bolted together on site because welding could not take place on the field. Traditional concrete footings could not be used because the greenhouses sit on the top layer of a bog that provided no lateral support. To prevent the greenhouse from sinking and shifting, bobcats installed helical screws at each post and at 45 degree angles. Due to the unique geometry of the structure, 3 dimensional modeling was used for the design and scale models were constructed by Albert J. Lauer to ensure everything fit together in the field. The majority of the site construction took place during the winter when the bog was frozen, allowing bobcats and other equipment to come in and move without sinking.
“Building a structure like this in a bog is challenging”, says principal structural engineer Matt Van Hoof, “not only do you have natural elements such as wind, snow, and special soil conditions that you have to account for from a structural perspective, but you are also working in a sensitive environment that the researchers wanted to control.” The greenhouse structures were successfully constructed this winter. “This was a really unique and exciting project to work on,” says Van Hoof, “and I am impressed with how well the project team overcame the unique challenges and was able to pull it off.”