Figuring out the best way to construct an architect’s design can be challenging for contractors, who may be limited by traditional building materials like concrete, steel and wood. In recent years, however, some architects and builders have turned to composite materials to remove constraints. The light weight and flexibility of composites can make FRP the material of choice for stand-out design features.
These four projects showcase the benefits and possibilities that composites can offer the building industry.
projects The Latitude office building
composite component: GFRP façade
Tasked with renovating and adding space to a 1970s-era office building, Studio Architecture designed a striking façade of curved ribbons that connect the original, newly glazed section and a new wing of the Latitude building in Paris. Construction was challenging for general contractor Bouygues Bâtiment Ile-de-France.
“Originally, the ribbon shapes were going to be made using thermal forming of thermoplastic plates with a steel structure inside,” says Samuel Durand, senior structural engineer and manager at the engineering/design firm Meca. However, the steel/thermoplastic ribbons would be too heavy, and Bouygues could not find a subcontractor capable of meeting the architect’s visual standards.
So, Bouygues worked with Meca and specialty chemical supplier Sika on a composite solution. Sika suggested blocks of freestanding polyurethane foam for the triangular ribbon shapes, using a heavier density of the material for longer spans. It joined the blocks with a fast-curing polyurethane resin, then had a subcontractor machine the lengths into individual ribbon shapes.
Next, subcontractors Le Prince Borel and SMM Technologies covered the tops and sides of the blocks with fiberglass fabric impregnated with an epoxy resin, SikaBiresin® CR82. It cured the ribbons at room temperature and then post-cured them at 50 to 55 C.
For the ribbon undercovers, Armacell supplied PET foam boards, which Sika sandwiched between two layers of fiberglass fabric and infused with SikaBiresin CR80 epoxy resin.
Finding a material that was easy to work with, durable and color-consistent to withstand long-term weather exposure was a challenge, says Patrick Noirclerc, composite products engineer at Sika. Since manufacturing consistency was another concern, Sika performed Meca-developed testing on a mock-up ribbon section, measuring properties such as tensile strength, thermal expansion, fatigue and mechanical junction strength.
Composites provided a cost-effective solution that gave the architects freedom of design.
“Glass reinforced concrete, or any other type of more conventional building material, would not allow this type of curves,” says Henri Chapelle, sales and marketing manager, PET foams, Armacell.
projects David Geffen Hall, Lincoln Center for the Performing Arts
Location: new York
Composite components: GFRP ceiling panels
Improving the acoustics of the Wu Tsai Theater was a primary goal in the renovation of Lincoln Center’s David Geffen Hall. Kreysler & Associates created the textured GFRP ceiling panels that helped achieve the desired sound.
Composites have become a favored material in performance spaces because they are configurable to acousticians’ detailed specifications. “Acousticians don’t like smooth, flat surfaces, because the sound bounces off of them in ways that can create echoes,” says Bill Kreysler, the company’s founder and CEO. “For most of the acoustical panels that we’ve done, the design calls for a pattern – a texture on the surface. The texture can be very organic, or it can be a very specific geometric pattern that creates a kind of three-dimensional relief surface, in addition to the panel itself being curved.”
For Wu Tsai Theater, architect Diamond Schmitt and acoustician Acoustics wanted the ceiling to resemble the space’s new perforated metal wall panels. Acoustics also specified that the panels had to weigh precisely five pounds per square foot.
“We were very involved in the surface pattern geometry to help the architect achieve what they wanted within the schedule,” Kreysler says. “Some molds took several hundred hours of CNC milling, so the mold milling time determined the schedule of the product.” The company added a proprietary concrete to the backs of the panels before removing them from the mold to achieve the desired weight.
Kreysler produced 40 GFRP panels using an open molded hand lay-up method. The panels varied in size from 4.5 x 8 feet to 20 x 10 feet. The total surface area is 4,200 square feet.
The panels were bolted to a frame that can be rotated to fine tune sound for different performances. That required careful engineering of the connections, which were embedded during molding.
“Since the panels need to rotate 90 degrees from time to time – and to be lowered and raised – and since there are several penetrations where light and rigging comes through, the engineering of the panel was fairly complex,” says Kreysler.
Geffen Hall’s official opening was scheduled for late October 2022. Preliminary tests of the theater’s acoustics won positive reviews from musicians and audience members.
projects The Heritage luxury apartment
Location: Sao Paolo
Composite components: GFRP exterior ornamentation
Pininfarina, an Italian firm known for car design, has branched out into architectural design. A recent project, the Heritage luxury apartment building in São Paolo, features dynamic, curved GFRP accents on the building’s 32 floors.
Project developer Cyrela asked the design/engineering firm Clamom to determine the best way to build the composite overlays for the balcony bottoms and 16 J-shaped forms that create a visual link between every other floor. Concrete would have required additional structural support, and aluminum composite materials would have required too many pieces, making it difficult to achieve the continuous, flowing lines that Cyrela wanted.
So, Clamom contacted Gatron, a composite manufacturer with experience in wind power, transportation, agriculture and other industries.
“The challenge was to be able to manufacture a piece with a sinuous design that was, at the same time, lightweight, weather resistant, with high dimensional stability, a minimum number of amendments [connections] and perfectly aligned to the balconies,” says Jean Zolet, executive director at Gatron. The maximum tolerance gap was 2 millimeters.
“Cyrela sent us the 3D drawings, and we worked together with them to adjust the drawings so that it was possible to produce the composite parts,” he adds. Gatron manufactured 47 molds to manufacture the balcony covers and the J-shape forms – each with a distinct geometry – using chopped strand fiberglass mats and a resin that met the required flammability standards. The forms were made using an infusion molding process.
The company produced 755 pieces, all with an automotive Class A finish. The largest piece was approximately 19.6 feet long, 1 foot wide and 13 feet high. The other pieces averaged 26.2 x 1.6 x 1.8 feet. Gatron produced an average of 20 pieces per day, which were then attached to the building using a special metallic fastening system that was embedded in the composite during molding.
Zolet says everyone involved in the project was pleased with the aesthetics and the performance of the composite components.
“We understand that the success of this project will bring new business, and we continue to work hard to close new business in this market,” he says. “We believe that in the next five years we will see a significant increase in the architectural market.”