Getting Architects on Board with Composites

The 8,000-pound bronze International Friendship Bell in Oak Ridge, Tenn., was installed in a park in 1996 to symbolize the spirit of peace and friendship shared between the cities of Oak Ridge and Naka, Japan. A newly-constructed pavilion added last year features freestanding CFRP beams over the bell that are also symbolic, representing a bridge between traditional design and radical innovation in architectural applications. The curved beams are not only eye-catching to the public, but they also provide an opportunity to educate the architectural community about the possibilities of composites. Even the architect who designed the beams had an eye-opening experience working on the pavilion design. “The architect mentioned that when it comes to new projects, he will start thinking of composites more in the future,” says Uday Vaidya, chief technology officer at the IACMI—The Composites Institute and UT-ORNL Governor’s Chair, University of Tennessee, who helped spearhead the project. Although composite materials have pushed boundaries in architectural applications in recent years, many architects remain largely unaware of the benefits of composites in architecture and how best to utilize FRP materials. Projects like the Friendship Bell pavilion are helping to educate them. “Finally, after years of missionary work, I think most architectural firms are now familiar with the term FRP,” says Bill Kreysler, president of the engineering and fabrication firm Kreysler & Associates in American Canyon, Calif. “Now it’s a matter of educating those architects and engineers about where and when you should and should not consider FRP.” A Striking Pavilion The park where the International Friendship Bell resides was renovated in 2018 to create a larger plaza around the bell and a pavilion where visitors could gather for thoughtful reflection. The curved beams, which are the world’s largest overbraided structure, were developed by several expert organizations in the composites industry. Knoxville-based IACMI brought together Oak Ridge National Laboratory’s Carbon Fiber Technology Facility, the University of Tennessee and the overbraiding experts at Highland Composites in Statesville, N.C. That local carbon fiber expertise, coupled with the innovative concept from Ziad Demian of Demian Wilbur Architects, gave composites an edge in being specified for the pavilion. Composites also provide the required stiffness to achieve the large length desired for the pavilion beams – 33 feet – as well as light weight, durability and easy installation. To park visitors, the pavilion may seem deceptively straightforward. Above the bell, 17 free-floating arched beams cantilever from a central concrete/steel superstructure. To create the appearance of an open dome for anyone standing beneath the structure, each beam features an entirely different arc radius. Because there was no consistency among the beams, molds were immediately ruled out. From there, the University of Tennessee/IACMI team was challenged to develop a cost-effective method for manufacturing 17 unique CFRP beams. “Many factors went into determining the easiest and cheapest way to produce this without a mold because it had to be a continuous chain for each different arch for the beam,” Vaidya explains. Ultimately, the team hit upon a combination of vacuum infusion, braiding and overbraiding. “Braiding technology is unique in that it’s able to bring in fibers from different angles and strengthen those based on direction,” Vaidya says. Each beam began with a high-performance polyurethane foam core that was curved to the desired shape. Next, the foam core was sent through a braiding machine where Toray T700 24K standard modulus carbon fiber was wrapped around the foam in a triaxial architecture. Finally, the overbraided form was vacuum infused with a thermoset epoxy resin, fully encapsulating the core. “This being a prototype, we learned as we went,” Vaidya adds. “It took us about six weeks to produce these 17 beams. I believe if this were an industrial scenario you could probably make them in a week.” The carbon fiber braided arched beams won the Award for Composites Excellence (ACE) for Most Creative Application at CAMX 2019. Advantages that Appeal to Architects The Friendship Bell Pavilion highlights one of the primary attractions of composite materials in architecture – their ability to create any shape. “Shape continues to be attractive to architects, and certain shapes are just problematic to do in concrete and steel and aluminum,” says Andy Bridge, vice president of industrial markets and director of research and development with manufacturer Janicki Industries. “So, architects find themselves intrigued by or having to turn to composites.” Sustainability also resonates strongly with architects, and this “green” focus could help garner greater interest in composites. While composite materials’ documented durability attests to the fact that it can lengthen a project’s lifespan, designers may be more interested in the integration of recycled materials to create architectural structures. The Meteghan River house in Nova Scotia, which Composites Manufacturing magazine featured in its September/October 2019 issue, is a case in point. JD Composites Inc. built a 2,000-square-foot waterfront home featuring engineered beams and walls made from Armacell’s 100% recycled PET foam panels. The product has been tested to withstand a Category 5 hurricane, achieves an R30 insulation value and diverted about 612,000 plastic bottles from landfills in the process. “There are at least five or six of these kinds of projects around the world on paper,” says Sam Ang, business development manager – Americas for foam manufacturer Armacell. The problem, he says, is that most people are waiting for government grants or other funding before diving into the testing needed to prove the benefits of a composites house. And, in a classic Catch-22, few of those grants are offered before testing proves the feasibility of a composites house. Tiny Homes, Big Potential The Composite Recycling Technology Center (CRTC) in Port Angeles, Wash., is testing that feasibility right now in a unique application. The organization has been working since 2015 to create new value from the roughly 50 million pounds of carbon fiber scrap typically sent to landfills. CRTC has manufactured portable pickleball nets, park benches and skateboards, and is now developing wall panels for the construction market. Together with Washington State University, The University of Minnesota – Duluth Natural Resources Research Institute, USDA Forest Products Lab, Oak Ridge National Laboratory and the Jamestown S’Klallam Tribe and Makah Tribe, CRTC has put together an initiative to take coastal western hemlock, thermally modify it and place it in a cross-laminated timber (CLT) that is integrated with recycled carbon fiber supports. The hemlock achieves mildew, rot and bug resistance, while the carbon fiber adds significant stiffness and strength to the interlocking wall panels, explains Dave Walter, CRTC CEO. “That [integration] allows you to get longer spans in thinner panels than you could just do with wood reinforcement,” says Bridge. CRTC has built a test panel and is conducting various tests to determine performance. Although the product is not yet commercially available, the patent-pending Advanced CLT system has been specified for the construction of 24 tiny homes, pending funding. The homes, ranging in size from 240 to 400 square feet, are slated for construction on a 7-acre Port Angeles parcel owned by Pennies For Quarters, a not-for-profit organization working to provide homes for members of the armed forces who have fallen on difficult times and are homeless. Once a home’s foundation is in place, Walter says that each tiny home can be built in less than three days using the Advanced CLT system. The warm wood walls eliminate the need for drywall and provide a strong, durable and well-insulated home. Each tiny home is projected to achieve an R32 insulation value in the walls and R40 in the ceiling. Ultimately, the project is targeting net-zero energy consumption. “This is a fantastic opportunity to assist our homeless veterans and show how an under-utilized timber species like coastal western hemlock can be combined with carbon fiber to provide an advanced building material that is very strong and durable,” Walter adds. “The combination of timber and tech is extremely exciting.” Bridge agrees: “That’s an area I’m watching because it’s an interesting way for composites materials to add some real value in a hybridization format.” Making a Structural Case Each of these homes further build the case for use of composite materials in structural applications. It’s a case that needs to be built, as Kreysler finds that the product’s strength-to-weight ratio is often overlooked. As Kreysler points out, composites are often specified for the stiffness they bring to a specific application. By the time the desired stiffness is achieved, the material is typically strong enough to provide structural benefits as well. “We’re beginning to utilize composites in what I call a quasi-structural way,” he says. “In other words, making bigger spans between edges or utilizing composites to take advantage of their strengths as well as their durability and formability. That’s where the next big breakthroughs are going to be made.” Such was the case for “A Gathering Place for Tulsa” in Oklahoma, which Kreysler completed in 2018. The park features a patio with an 8,000-square-foot composite canopy, comprised of 130 sail-shaped, curved panels. (Composites Manufacturing magazine featured the project in its March/April 2017 issue.) Kreysler created each panel with a polyester resin and fiberglass skin around a balsa core. The resulting roof is stiff enough that the FRP supports itself; vertical steel columns hold the canopy over the patio below, but it’s the only use of structural steel. “Meeting the wind loads required to make that roof stay up was done by the composite material itself, which is unique,” says Kreysler. More composites fabricators are looking to test these loads. While Janicki Industries has proven that composites are a suitable roofing material on numerous dome projects, the company is now developing a composite monocoque structural roof panel that is infused as a single piece. Bridge notes that applications may include living roofs, where this design could replace existing multi-layer approaches with a single strong, lightweight structure. Poised for Growth Composite materials are poised for growth in the architectural industry, and there’s plenty of room for more industry companies to jump on board and support that growth. “The fact of the matter is there are only a handful of people and companies that are really designing and fabricating composites for architecture,” says Ang. When end users vocalize an oft heard concern – the high cost of composites – manufacturers need to be ready to respond with compelling arguments about the extensive benefits of FRP. The more fabricators that invest in architectural solutions, the more compelling the argument for architects to specify a composite product in their next landmark project.