by Alex Legé Valerie Hendel
Tacoma, Washington | On Saturday, October 20, 2018 Tacoma’s new Eastside Community Center opened to the public. The enthusiasm for the project goes to the heart of the community that experienced the need for a safe and vibrant community space and the participants that embraced that need.
The design and structural engineering of Eastside Community Center mirrors the vision, emotion, innovation and collaboration that made the idea a reality. It took layers of community support to see get it built—The East Side Community, Metro Parks, Tacoma Public Schools, Greater Metro Parks Foundation/Boys and Girls Club, Tacoma Housing Authority, Tacoma/Pierce County Health Department, and city and state programs.
Eastside Community Center Design
The vision for the design was created from the dreams of the community of people who would use the space. More than just a youth center, it had to support an impressive swath of multi-generational activities. The center is home to a 318,000-gallon swimming pool, basketball court, training kitchen, meeting and classrooms, social hall, sports and fitness areas, dance room, coffee shop, and recording studio.
Designing a space that would function well for the variety of programming at Eastside was a challenge, and the aesthetic had to feel inviting to users. Beauty and warmth was integral to every decision. Exposed structural elements set the aesthetic of the project. The teams of ARC Architecture and PCS Structural Solutions chose Cross-Laminated Timber (CLT) to add warmth, help connect visitors to entrances and provide functionality.
Cross-Laminated Timber (CLT)
The excitement CLT generates is a no-brainer in the Pacific Northwest. CLT speaks to place—to a region where trees largely defined its economy and certainly define its aesthetic identity. CLT also adds value as a material because it appeals to the Northwest interest in pursuing and integrating sustainable solutions. Cross-Laminated Timber lends to outside-in interior styling, and its ability to span in two directions allows for unencumbered exterior lines. Its crosswise construction provides inherent strength to a thin profile.
Paul Curtis, lead architect for the project explains, “At Eastside, CLT spans were used around the perimeter of the building and ‘lifted up’ to highlight entrances and other locations where a strong indoor-outdoor connection was desired. The beautiful and warm wood color acts as a marker, and the continuous and uninterrupted plane emphasizes connections to the outdoors. CLT also was a practical choice where groups of people congregate outside in the elements. “We were able to provide the covered areas called for by the program with minimal additional structure needed.”
At the Eastside project, CLT solved another problem. Curtis explains, “Due to the sensitive nature of pool environments, continuity of the building envelope was very important to the design team. Fewer penetrations means fewer opportunities for air, vapor and water leaks.”
Innovating the Details for CLT
While CLT has been on the global scene for some time, its use in the U.S. is relatively new. The industry is still fine-tuning best-use practices, and there is limited standardization. CLT was the perfect design choice for the project design goals, but it presented detail challenges that put the project squarely in PCS Structural Solutions’ bailiwick. Details for CLT are relatively non-existent. “We had to invent the details,” says Jim Collins, principal and project manager at PCS Structural Solutions.
The Challenges
The design called for CLT to span in two directions and to be attached directly to steel. Transferring lateral shear forces also proved a critical challenge—how to keep the building all together in the case of seismic activity? An additional layer of plywood above the CLT to serve as a diaphragm would have been required, adding time and materials cost.
Connections
The structural design challenge of attaching CLT to steel came down to connections. More than a textbook structural engineering problem, the detail would directly impact the aesthetic because the structure is exposed to view. The structural engineering solution had to seam flawlessly with the design.
PCS developed a sloped, welded plate and MyTiCon-screw assembly to attach the CLT roof to the steel structure. An effective and elegant solution, it satisfied code and did not intrude on the design.
Another type of connection proved critical to solving shear: collaboration. Through collaboration with the designers and CLT manufacturer, PCS solved for the load issue and ensured that the roof would maintain integrity without the additional plywood layer. “This is a new technology,” says Alex Legé, structural engineer with PCS Structural Solutions. “For it to be successful, there has to be strong collaboration between the engineers, designers and manufacturers.”
“PCS Structural Solutions has used CLT successfully on several projects and is developing solutions that allow this ordinary element to be used in extraordinary ways,” says Jason Collins, principal at PCS Structural Solutions. “It’s exciting to pioneer connectors and create elegant solutions that promote the aesthetic.” In Tacoma, Washington, the Eastside Community Center is the first project to open using CLT. “Our next project using CLT is the Port Angeles Pool Project. We’re excited for the opportunity to build relationships and move new solutions to the industry as it embraces CLT.”
Look to Cross-Laminated Timber’s appeal to help define modern Pacific Northwest Architecture style. To view projects in the Pacific Northwest using CLT, visit pcs-structural.com and arcarchitects.com.
photos by Janette Ryan
