Posts tagged with "PTFE":

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Fabrics could be the next big thing in facades

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Humans have been using fabric to create shelter for thousands of years. If a set of groundbreaking researchers and designers have their way, however, applications of textile-based architectural elements have the potential to play an important role in shaping the future of enclosures as well. Across scales and methods of application, research into the use of textile-based elements in architecture has increased over the last 15 years as professional and university teams in Europe and the United States have embraced robotic weaving applications, custom-designed carbon fiber textiles, and experimental fabric facades. With an eye toward wrapping ever-larger structures, creating unique sensory experiences, and engineering a more sustainable future, new applications of fabrics have the potential to change the face, look, and feel of architecture as we know it. Fiber Composite Dome Institute of Building Structures and Structural Design
Universities in Germany are leading the charge, especially at the Institute of Building Structures and Structural Design (ITKE) in Stuttgart, where Professor Jan Knippers has developed methods for creating textiles from bendable composite elements, including carbon and glass fibers. Knippers is currently working on develop- ing the latest iteration of his Elytra pavilion, a Fiber Composite Dome prototype structure that will make its debut at the National Garden Show in Heilbronn, Germany, later this year. The 40-foot-wide dome is made of woven glass carbon fiber elements connected only by steel washers and bolts. To create the pavilion, Knippers has designed a geometric array of 60 resin-impregnated fiber body assemblies that come together to distribute structural loads from the dome elegantly and efficiently. The precision-driven arrangement also extends to the size and organization of each strut’s individual carbon fibers, which are robotically arranged into place, baked in an oven until stiffened, and finally assembled into taut spanning assemblies. When erected into the final spherical shape for the pavilion, a secondary shell made of ETFE polymer is added on top for protection from the elements.
CRC1244 Demonstrator Institute for Lightweight Structures and Conceptual Design
Building-scale research is also taking place in Germany, where Dr. Walter Haase, managing director of the Collaborative Research Center (CRC1244) at the Institute for Lightweight Structures and Conceptual Design (ILEK) in Stuttgart is really pushing the envelope. Fourteen university-based research teams are working there to develop ways to “create more living space with less material” by using fabric-based facade and building elements to drive innovation in overall building design. The group is currently building a 120-foot experimental modular tower that will serve as a testing site for new fabric-based facade and building technologies that could transform the way buildings are designed, fabricated, used, and even recycled.
The elemental steel strut and concrete tower exists to test out new material approaches for each of its square-shaped levels, with a specific focus on folded surface structures, innovative processing of conventional fabrics, geometrically deformable structures, and origami-inspired folding structures that can be used to create lightweight sandwich panels. The tower is designed with flexibility in mind so that fabric-based facades developed by academic and industrial project partners can be tested and switched out as necessary in the coming years. Allianz Field Populous
In terms of real-world applications, fabric-based architectural strategies are coming to lighting as well, especially in the realm of stadium design, where membrane materials like PTFE and other custom fabrics are used to wrap wide and often curvilinear stadium geometries with ease. The Populous-designed Allianz Field soccer stadium in Minneapolis, for example, features an 88,000-square-foot transparent and laminated custom PTFE fabric facade created in partnership with fabricator Walter P Moore specifically for this project. Stretched over a parametrically designed steel rib substructure, the fabric facade is backlit with 1,700 emotive LED lights that can be programmed to glow for various occasions.
Populous is also behind the Daily’s Place Amphitheater and Flex Field project in Jacksonville, Florida, a unique dual-use space that blends a performance amphitheater with a practice football field. There, fabric roof panels are hung from steel trusses that frame the space. The outer steel structure allows for a monolithic fabric ceiling that can be bathed in LED light. Social Sensory Architectures Lab for Material Architectures
At the University of Michigan A. Alfred Taubman School of Architecture and Urban Planning, for example, Sean Ahlquist is working across disciplines and with industrial and corporate partners to develop articulated material structures and design approaches that “enable the study of spatial behaviors and human interaction.” Ahlquist’s research focuses on using computational design and fabrication to create structures and spaces that move “beyond materialization” to focus on “sensing, feedback, and engagement as critical factors of design exploration,” according to a recent scholarly article he wrote. Using CNC knitting, hybrid yarns, and other digital fabrication techniques, Ahlquist’s research team is able to generate pre-stressed lightweight structures, innovations in textile-reinforced composite materials for aerospace and automotive design, as well tactile sensory environments that can act as “interfaces for physical interaction.”
A recent project for Exhibit Columbus in Columbus, Indiana, creates custom textile micro-architectures by manipulating fibers and stitches to generate “instrumentalized, simultaneous structural, spatial, and sensory-responsive qualities” in fabric structures that can be used by children with autism to filter and manage multiple sensory inputs.
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Allianz Field, Minnesota United’s new home, glows with PTFE-coated facade

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Completed in March 2019, Allianz Field is a 346,000-square-foot soccer stadium located centrally between Minneapolis and St. Paul, Minnesota. The project was executed by Populous, Walter P Moore (WPM), Mortenson Construction, and FabriTec Structures, and it features a facade of woven fiberglass clear-laminated with polytetrafluoroethylene (PTFE)—effectively a tensile membrane capable of shielding the audience from the elements while transmitting twice as much light as other PTFE membranes.
According to the design team, the client initially approached Populous and Walter P Moore to produce a stadium with a translucent facade. The group was aware of a clear PTFE laminate being developed by French manufacturer Saint Gobain—now known as Illuminate 28—and facilitated the shipment of moderately sized samples from the company. These samples were used to construct a 6-by-6-foot mockup with the material to gauge its tensile and lighting qualities. The design and construction of the stadium occurred as the facade material was being developed.
  • Facade Manufacturer Saint-Gobain
  • Architect Populous
  • Facade Installer Mortenson GC FabriTec Structures
  • Facade Consultant Walter P Moore
  • Location St. Paul, Minnesota
  • Date of Completion March 2019
  • System PTFE-coated fiberglass membrane suspended over steel structural system
  • Products Illuminate 28
The enclosure system of the stadium consists of three interconnected layers: the exterior skin of PTFE-laminated fabric, a secondary backup system of steel driver pipes and armatures, and a circular colonnade of steel columns.
In abstract terms, this enclosure system sounds simple enough. However, unlike rigid cladding materials, the tensile strength of fabric is ultimately determined by the 3-D shape it is stretched into. “We never knew if our fabric shapes would work or not from an engineering standpoint until after the design was complete,” said Populous associate principal Phil Kolbo. “To achieve the design, Populous and WPM had to set up a cohesive process that could design, test, and modify the supporting steel quickly and iteratively to satisfy both the design and engineering requirements of the skin.”
In total, over 90,000 square feet of fabric wrap the stadium. Due to budget constraints, the design team had to maximize the spans between structural components. Utilizing Rhino and Grasshopper 3-D imaging software programs, WPM created nearly 50,000 analysis elements to locate sites where the fabric was overstressed. This information was then exported from Rhino to Tekla software and delivered to the steel fabricator.
“Once we had a fabric and driver pipe design, then it was supporting the process throughout getting the owner, Mortenson, and FabriTec comfortable with the material and construction process,” said Walter P Moore principal Justin Barton. “It started in February 2016 and went all the way through FabriTec’s final installation and punch list in late 2018, nearly 24 months of continual conversation.”
Populous Associate Principal Phil Kolbo, Walter P Moore Project Manager Justin Barton, Mortenson GC Project Engineer Nate Weingart, and FabriTec Structures Executive Vice President Tom Wuerch, will be joining the panel "Stadium Rising: The Complexities of Allianz Field’s Woven PTFE Facade" at The Architect's Newspaper's upcoming Facades+ Minneapolis conference on July 24.
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New naturally-ventilated Louis Armstrong Stadium debuts at US Open

Today tennis takes over the world’s stage with the start of the 2018 US Open. Now in its 50th year, the tournament will play out within the newly renovated USTA Billie Jean King National Tennis Center in Flushing, Queens. The five-year, $600-million project is now finished with the opening of the site’s final project: the Louis Armstrong Stadium, the world's first naturally ventilated tennis arena with a retractable roof. Over the next two weeks, hundreds of thousands of fans will descend upon the city to watch the final Grand Slam of the year, and while the tennis champions themselves are the real stars of the show, the stadium architecture will be prominently on display. The highly-anticipated renovation marks the end of the site’s fraught history with deteriorating courts and rain delays messing up major events.     Designed by Detroit-based firm Rossetti, the new 14,000-seat Louis Armstrong Stadium evokes the feel of the old arena, which the USTA opened in 1978, but includes modern feats of engineering and sustainable design additions that bring it into the 21st century of sports architecture. The stadium boasts 40 percent more seating than its predecessor in two levels of precast concrete bowls and an advanced shading system that’s anchored by a fixed, cantilevered roof deck. Matches can proceed rain or shine thanks to the masterfully-engineered two-piece, moving roof that covers the court. Called a “complex, stackable sun room” by the architects, the retractable roof features 284,000-pound PTFE fabric panels that create a 38,160-square-foot opening after traveling 25 feet per minute in under seven minutes from the stadium’s edge. The transparent, lightweight fabric diffuses a soft light into the arena when closed, transferring 73 percent of the sun’s energy. The sides of the stadium additionally allow breezes to flow through the facility. Rossetti placed 14,250 overlapping terracotta louvers on the north and south sides of the structure that act as horizontal window blinds. The siding material is a nod to the traditional brick buildings found throughout the tennis grounds. Construction began on the new stadium two years ago when the 52-year-old Armstrong arena was demolished after the 2016 championship. Originally built for the 1964 World’s Fair, the structure was much-loved because it gave fans an intimate experience and unbeatable views with sky-high, stacked seating. Louis Armstrong Stadium 2.0, as many are nicknaming it, does the same but with a more porous, contemporary design. Plus, it has a built-in umbrella that ensures consistency of play no matter the weather. To celebrate its opening, Armstrong will hold more matches during the 2018 US Open than its neighboring Arthur Ashe Stadium, an 18,000-seat arena that also received a flexible roofing system during the renovation. Both stadiums will hold two matches at night, but Armstrong will see three during the day while Ashe will host two.
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Populous expands the Jacksonville Jaguars brand beyond sport

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Designed with community and connectivity in mind, Populous has recently completed an amphitheater and flex field adjacent to the Jacksonville Jaguars’ professional football stadium. The project, named Daily’s Place, is the first amphitheater integrated with an NFL stadium in the country. With the grounds of the stadium active only a handful of times per year, the project is a response to a desire to activate the stadium area beyond football season with training events, concerts, festivals, and more.
  • Facade Manufacturer Verseideg and Saint Gobain; 
  • Architects Populous
  • Facade Installer Banker Steel (steel); Structurflex (fabric)
  • Facade Consultants Walter P Moore (envelope and facade consultant)
  • Location Jacksonville, FL, USA
  • Date of Completion 2017
  • System PTFE over steel frame
  • Products Sheerfill 2 PTFE (Roofing); Verseidag PTFE (Wall cladding)
Two column-free large event spaces—composed of more than 80-percent fabric and steel—were delivered under a close collaboration between design and engineering teams. The entire facility is covered under one all-encompassing PTFE roof system manufactured by advanced polymer technology company Saint-Gobain. The composite membrane, called SHEERFILL, is made of fiberglass and polytetrafluoroethylene (PTFE) typically used as a permanent tensioned membrane structure in sports, transportation, retail, and specialty markets. Design, engineering and fabrication teams used the software in an unconventional way to blur the lines between design and detailing with construction and fabrication modeling. Populous consulted with Walter P. Moore, an international A/E firm, who provided envelope and facade engineering expertise. Erik Verboon, Principal at Walter P. Moore, said the project was very fast pacing, involving a "fluid" digital process. "This could have only been completed under a close collaboration with Populous and a digital workflow that we both harnessed." Design and construction models were shared back and forth between the design and engineering teams, involving an iterative series or Rhino and Grasshopper models. While Populous managed the formal strategy of the project, Walter P. Moore worked through model analysis and optimization that involved engineering and form-finding techniques. The facade involves a series of "V" shaped perimeter columns set inboard from the exterior envelope. The materiality of the skin began as polycarbonate panels, but evolved into an open mesh PTFE fabric to save steel tonnage that the smaller more rigid polycarbonate panels would have required. Above, an undulating roof of Daily’s Place passively cools the interior of the facility by controlling air movement. The resulting “roofscape” integrates LED lighting to highlight its wavelike form, introducing a customizable aesthetic element that can be adjusted dependent on programming. As a result of the scheduling of the project, ordering of the steel framework was on a critical path, however, the sizing and detailing of the steel was highly dependent upon the configuration of the PTFE fabric. Due to this, Verboon said the engineering of the system relied on "coupled models" which dynamically take both structural requirements of the PTFE fabric and steel framing into consideration, producing an optimized, efficient design. "The steel was based on loads of the fabric, and the fabric was based on the geometry of the steel. The two materials were intrinsically linked." (Courtesy Populous).One of the most challenging aspects of the detailing of the building envelope was the location of the roof membrane, which sits below long span trusses. The positioning of the membrane produced translucent ghosted effect, softening the visual impact of the structure, but resulted in detailing challenges with necessary penetrations from steel rail supports and the perimeter structure. At these columns, a unique "top hat" detail, involving a circular flange surrounding a steel drum, developed to ensure a watertight connection.  
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Fabric screen connects tennis stadium to surrounding park

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Located adjacent to the New York State Pavilion—the host of the 1964 World's Fair—the USTA Billie Jean King National Tennis Center hosts the annual US Open Tournament, one of the oldest tennis championships in the world. In an effort to better utilize the sports campus, Detroit-based ROSSETTI developed a master plan to move the Grandstand Stadium to a far corner of the grounds. The relocation expanded USTA's leasable land into Flushing Meadows Corona Park.
  • Facade Manufacturer Birdair
  • Architects ROSSETTI
  • Facade Installer Birdair
  • Facade Consultants Birdair; WSP (structural engineer)
  • Location Queens, NY
  • Date of Completion 2016
  • System steel frame with PTFE fabric
  • Products custom made PTFE fabric
To mediate between this historic park setting and the tennis campus, ROSSETTI designed a unique exterior skin pattern that metaphorically evokes the translucency of leafy tree canopies and the twisting dynamics of the tennis serve. The material selected, a Teflon-coated fiberglass membrane, polytetrafluoroethylene (PTFE)­, is typically used for roofing applications but in this case, a woven version allows for a more translucent breathable effect. The facade assembly is composed of 486 panels, totaling over 26,000 square feet, that fasten to a cable structure with parametric geometry. The system was designed with computational solver software to streamline design and constructability, ultimately saving an enormous amount of time and money in the project. Matt Taylor, design lead at ROSSETTI, said that early on in the design process, the team tried to mimic the faceted geometry of the structure, by ultimately ended up with a curvilinear form: "Even though this was a very complex facade, we had to simplify it to a point where it was repeatable, structurally feasible, and that the detailing could be economic enough to stay within budget." Pierre Roberson, a technical designer at ROSSETTI, led the effort to optimize and simplify detailing of the system. He said the structure of the building was not symmetrical but rather based on spline geometry with an infinite number of radii, and that the key to optimizing the facade was about producing a series of modular components that approximated the perimeter shape. Roberson split the spline of the ring beams into 16 equal segments, finding optimal radii for each segment. After optimizing the beam geometry, Roberson used Galapagos, a parametric tool in Grasshopper3d, to find an ideal strut length from over 1,000 of the individual panel supports. This process standardized the length and angle of the facade strut geometry, which allowed the team to provide models for the shop fabricators, who were able to attach connection points to the ring beams at the same angle. Early on in the process, working with PTFE manufacturer Birdair, ROSSETTI mocked up details using PVC pipes and in-house 3d-printed connection components to test and resolve details in full scale. This became a transportable design, presentation, and technical tool that allowed the connection between the PTFE panel and the steel strut to evolve into an elegant functional expression. Taylor said the mockups led to design changes through a collaborative process between the architect and manufacturer. "Birdair was great to work with—they were up to the challenge of this design." The actual fabric shapes were directed by Birdair’s dimensional and formal requirements. For example, a doubly-curved surface geometry is easier to tension than a standard planar surface. Also, by maintaining a specific dimension of 5-by-10 feet avoided the visual clutter of seams running through the panels. "We could have specified a large panel size and worked a secondary seam pattern onto the panels, but we thought this was a much more elegant solution," said Taylor, adding, "there's something really nice about the pedestrian scale of the panels."
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Arthur Ashe Stadium's new PTFE retractable roof can open or close in just six minutes

Arthur Ashe Stadium at the U.S. Tennis Association (USTA) Billie Jean King National Tennis Center in Queens recently unveiled its new retractable roof as well as numerous changes and additions to the tennis complex. Finished in time for this year’s U.S. Open, the roof and master planning of the rejuvenated site was served up by Detroit-based firm Rossetti.

Spanning 236,600 feet, the polytetrafluoroethylene (PTFE) waterproof roof primarily will be used to cover the court during periods of rainfall and is able to open or close in under six minutes. USTA executive director and chief operating officer Gordon Smith said it “remains to be seen” if the roof will be used as a shading device, later adding that the USTA’s “overriding goal is to be an open court tournament at all times.”

To counter water run-off issues, a 15-foot-wide and 4-foot-deep metal gutter traces the structure’s perimeter. Meanwhile, an attached power unit will aid temperature regulation and run the roof’s opening and closing system.

The new Grandstand stadium was built as part of the site’s master plan. The new 8,000 capacity venue uses a PTFE skin to form a partial bowl around the arena, intended to emulate the foliage of the stadium’s surrounding greenery. For more information on this development, see our full article here.

Arthur Ashe Stadium Billie Jean King National Tennis Center Flushing Meadows-Corona Park, Queens, NY Tel: 718-760-6200 Architect and engineers: Rossetti
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Populous unveils design for Minnesota United FC's stadium

Major League Soccer’s newest expansion team, the Minnesota United FC, unveiled the first renderings of its planned 20,000-seat stadium. Designed by Kansas City–based stadium experts Populous, the field is expected to be complete by the start of the 2018 season in the Snelling-Midway neighborhood of St. Paul. The outdoor stadium will be enveloped in an LED-illuminated translucent PTFE (polytetrafluoroethylene) facade, which will act as a shade for the spectators.

Currently the proposed site, a parking lot for city buses, is not so fondly referred to as the “bus barn.” But the team believes the location, outside of downtown, can grow with the team and that the stadium can help give the area an identity all its own. Much to the praise of the public, the team plans to privately finance the entire $150 million budget, a departure from the economic model of most stadiums. Once completed the stadium will become publicly owned. Plans for the surrounding area have also been unveiled, including mixed-use retail, office, and residential developments. Completion is scheduled for 2018.

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Sonoran Desert Vernacular by CO Architects

Red-rock mountains and the saguaro cactus inspired the Health Sciences Education Building's rippling copper facade.

Downtown Phoenix, observed CO Architects’ Arnold Swanborn, looks a lot like downtown Minneapolis. That feels wrong, given the two cities’ contrasting environments. So when it came to designing the Health Sciences Education Building (HSEB) at Phoenix Biomedical Campus (which won honorable mention for facades in AN’s Best of Design Awards), CO Architects went back to nature—to the Sonoran Desert in particular. “We’re building in a desert. We really, in the outset, wanted to understand what it’s like to build in a desert environment, to really go back and investigate the people who first moved there, or even some of the [American] Indians who lived [there],” said Swanborn. “The skin is really a response to some of the lessons we learned from going out to the desert, being out there and seeing how plants and animals adapted to that environment.” HSEB’s undulating envelope, comprising 5,972 copper panels and more than 10,000 copper parts, echoes two of the defining features of the Arizona desert. First is the omnipresent saguaro cactus, which evolved a folded skin as a self-shading structure. Second is the layered soil of the nearby mountains. “[T]he [building’s] skin folds in a way that’s similar to the saguaro cactus,” explained Swanborn. “How we emulate the mountains beyond is by creating a shadow pattern by folding and articulating the metal panels.” Copper was a natural choice for the exterior cladding. HSEB went up during the recession, said Swanborn, “when everyone was very sensitive to making sure everything was local.” Copper is one of Arizona’s “five C’s”: copper, cattle, cotton, citrus, and climate. In addition, copper is highly conductive, meaning it responds quickly to the region’s aggressive swings in temperature. “Because it’s a rain screen technology we innovated into a sunscreen, there’s a space between the copper skin and building envelope,” said Swanborn. “There’s a 2 ½- or 3-inch air cavity that essentially acts as a chimney. The air gets superheated, and it essentially creates a vertical convection effect, which wicks heat away from the building.” On a 100-degree day, the copper skin keeps the interior a (relatively) cool 70. Finally, copper ages well. “Over time it patinas beautifully,” said Swanborn. “It’s easy to take care of; it kind of takes care of itself.”
  • Facade Manufacturer Kovach Building Enclosures
  • Architects CO Architects, Ayers Saint Gross (Associate Architect)
  • Consultants Transsolar (Climate Engineering)
  • Location Phoenix
  • Date of Completion 2012
  • System copper rain screen with sunshades and PTFE canopy
  • Products Kovach Building Enclosures custom copper panels and sunshades, Trenwyth Industries (Oldcastle) Trendstone ground face masonry units, Viracon VNE1-63 glass
Phoenix’s climate informed every aspect of the exterior design, starting with the massing. CO Architects worked with Transsolar to determine a shape that would maximize shading. The building is arranged around a narrow courtyard running from east to west, which the architects modeled on the Sonoran desert’s slot canyons. The courtyard is topped with a polytetrafluroethylene (PTFE) shading structure, which “allows daylight to filter through—sort of like a big lightbulb,” said Swanborn. “It filters, diffuses, and bounces off the interior’s light-colored walls.” The courtyard walls are faced in Trendstone ground face masonry units by Trenwyth, a light block rain screen used as a veneer. The courtyard helps bring light to HSEB’s east and west faces, which CO Architects left windowless in order to reduce thermal gain. On the south side of the building, they installed cantilevered copper sunshades over the windows. Vertical copper fins on the north elevation shade occupants from the rising and setting sun. Like the building’s copper cladding, the sunshades and fins were fabricated by Kovach. To open the ground floor on the west end of the building to the adjacent campus green, CO Architects took a cue from early desert dwellers. “When the [American Indians] first settled, they built underneath these carved rock formations, which again becomes self-shading,” Swanborn. The ground floor is glazed, but set back under the building to reduce direct exposure to the sun. Swanborn relished the challenge the joint University of Arizona/Northern Arizona University project provided. “To me the story’s really about the idea of creating a new urban vernacular for the desert,” he said. “The more restricted things become, [the more] architects have to become inventive. The skin of the building is really a pointer to that: it’s inventive, it’s innovative. I think it’s very fitting for that area.”