The Idaho Central Credit Union Arena at the University of Idaho (U of I) in Moscow features a specially designed double-curved roof in a long-span format made of wood. The engineering team behind the project worked to develop, shape and optimize the curved roof, ensuring its feasibility for manufacturing and construction.
This painstaking process not only enhanced the architectural vision, but also addressed the various limitations and challenges associated with a double-curved structure spanning 5,760m.2 (62,000 square meters). The architect, Opsis Architecture, envisioned the roof shape to be inspired by the rolling, mountainous landscape of the Palouse region, which spans parts of northern Idaho, southeastern Washington state, and some areas of northeastern Oregon.
Using wood in a double-curved roof and a structure composed of hybrid wood/steel trusses spanning 120 feet (36.6 m) brought its own set of challenges, but StructureCraft’s structural engineering team worked together with the architect to find a suitable solution. The solid wood sourced and installed by StructureCraft featured in this project includes long-span roof trusses, glulam columns, and cross-laminated and stud-laminated floors. KPFF Consulting provided structural engineering for the building’s foundation, and Hoffman Construction Company was the general contractor.
In the arena, carefully designed, meticulously proportioned 3D wood/steel trusses span a length of 150 feet (45.7 m), reaching a distinctive timber portal frame arch that delineates with grace the intimate space of the arena. Constructed of locally sourced lumber, this newly constructed structure has quickly transformed into a beloved exhibition space, showcasing the pride of the university and Idaho’s important forestry industry.
The project used primarily locally sourced Glulam, with curved Glulam members produced by two different manufacturers based in Idaho. This posed a significant challenge, as these manufacturers had not previously worked with the precise tolerances required for a project of this magnitude. However, according to StructureCraft, the structural 3D model produced by their team successfully generated all the geometry and shop drawings needed to produce the unique curved shapes of Glulam.
To achieve this, the engineer’s shop team leveraged their in-house CNC capabilities and used design optimization techniques to precisely cut the desired shapes from actual curved levers received from manufacturers of ‘Idaho. Additionally, the team carefully performed a “fit test” of each major assembly in the shop to ensure proper fit before shipping the components to the build site.
To minimize work at height, the entire portal frame was pre-assembled on site in three components, each weighing more than 22,679 kg (50,000 lbs).
The kingpost trusses presented a significant challenge during installation due to their weight and the need for a crane inside the bowl. To overcome this obstacle, a parametric model of the trusses was developed using genetic algorithms. This allowed for structural optimization while adhering to various aesthetic goals. As a result, the trusses achieved improved structural efficiency, significantly reducing the weights of the prefabricated elements. This approach not only kept the project on budget, but also ensured its successful completion.
