The tessellated geometry is both complex and structural, echoing the exposed excavated ruins in the entrance while providing support to the roof above.
In 1998, workers constructing an industrial park on the outskirts of Fukushima, Japan, made one of the largest archaeological discoveries in the country’s modern history. The ruins at Miyahata, which date back to Japan’s Jōmon period (circa 12,000 B.C. to 300 B.C.), are among several recent major archaeological finds that have begun to shed light on Japan’s prehistoric civilization, a hunter-gatherer culture credited with making some of the world’s earliest ceramic pottery. (“Jōmon” is derived from the cord markings of the civilization's ornate pots.)
Japan’s first museum dedicated to this period opened on that site last year, about 15 years after the original design competition was held. The winners, Tokyo-based Furuichi & Associates with Suzuki Sekkei, designed the 12,400-square-foot museum as a two-story, concrete structure whose main entrance hall sits atop the excavated ruins, which are illuminated and on display courtesy of an expansive glass floor.
Shigeo Ogawa
Mirroring the irregular terrain of the exposed ruins is a dramatic ceiling-scape made of jagged wood panels that recalls the cave dwellings first used by Jōmon societies. These communities later built villages of earthen pit-houses with timber frames, a detail that inspired Furuichi & Associates’ use of wood. The ceiling panels are structural, acting as truss-like members in a complex space frame and creating one of the first true wood-panel structures in Japan. “Even architects … ask me, ‘Is it just a ceiling?’ ” says Tetsuo Furuichi, the firm’s founding principal. “I say, ‘No, this is structure.’ Nobody thought it was structural. It looks like finishing only.”
The geometry of the wood panels derives from the pottery typical to the Jōmon culture. The architects abstracted the flared shape of a “flame pot”(named for its flame-like ornamentation) into a hexagonal pyramid, forming an inverted wooden cone that they repeat to create the tessellated structure, which supports a gable metal roof that floats above the 2,900-square-foot entrance hall.
Designing the panel structure was as complex as it looks. “We were very confused at first,” Furuichi says, “but with the help of the computer, we found some rules.” The architects used Vectorworks to create a structure from three unique types of cones, each of which is made up of six kite-shaped panels, but the digital model was still too abstract. “We couldn’t understand the actual space on the computer so we started making a [physical] model,” Furuichi says. “We made many models.”
However, the models weren’t enough to prove the design’s structural soundness to local government officials, who refused to issue a building permit until Masahiro Inayama, a well-known structural engineering professor at the University of Tokyo and timber expert who had collaborated on the museum’s final design, personally reassured the officials of its integrity. The museum’s future was also imperiled by the 2011 earthquake that destroyed the Fukushima Daiichi Nuclear Power Plant, just 40 miles to the southwest. Before construction began in 2013, the museum’s site was stripped of its soil and tested for radiation.
Once the design was approved, it took three months to build the wood roof structure. Comprising pine-glulam top and bottom chords, offset by approximately 9 feet, the base truss ties into the museum’s primary concrete structure via two wide-flange steel beams that top the walls flanking the entrance hall. The lower chords consist of two 14-inch-wide, 4.7-inch-deep beams attached with mitered joints. The upper chords comprise two adjacent 12-inch-wide, 6-inch-deep beams with angled notches through which the pyramids’ apices pop. The chords are concealed from visitors below, preserving the crystalline effect of the repeating cone shapes, which are roughly 8 feet tall and 9 feet in diameter.
Shigeo Ogawa
Each panel is made from 1.2-inch-thick medium-density fiberboard and ranges between 6 and 12 feet long, and between 4 and 9 feet wide. Fabricated 20 miles from the site, the panels are glued together and screwed into perimeter 2x4s. Like the lower chords, the panels’ edges are mitered to make the joints appear seamless, though many of the angles were adjusted on site by the general contractor, Ando-Gumi, which has experience working on Japan’s historic shrines and temples. Anyone who does such work “has a very good hand,” Furuichi says.
Where the ceiling cantilevers outside the museum’s exterior wall, the structural wood panels were painted with a transparent finish coating (Telios Coat, by Nikko) to protect the wood from moisture and humidity. Inside, the panels are finished in 5-millimeter-thick sheets of high-quality, flame-retardant plywood veneer. Furuichi wanted to leave structural panels exposed, in a nod to the rough timbers used in Jōmon pit-houses. Building codes required a fire barrier, however, making the plywood a necessity. “I’m a little bit disappointed,” Furuichi says half-jokingly. “This wood structure is too beautiful.”
Timothy A. Schuler is a contributing editor at Landscape Architecture Magazineand writes about architecture, landscape architecture, and urban design for a variety of national and international publications. Based in Honolulu, he is a graduate of Kansas State University. Follow him on Twitter or visit timothyschuler.com.
For further information log on website :
http://www.architectmagazine.com/technology/detail/miyahata-jomon-museums-faceted-ceiling_o
Spanning up to 188 feet, the structural components pushed the potential of wood in architecture while enabling a thin roof system perfect for a natatorium.
The Grandview Heights Aquatic Centre’s roof system wasn’t supposed to be wood. The cables that support the gently undulating system topping the Surrey, British Columbia, building were designed as steel, to be anchored into concrete slabs topping V-shaped concrete pylons to form a catenary structure, with wood infill. Then Vancouver-based structural engineering firm Fast + Epp noted that wood alone could support the roof’s tensile loads. This “aha” moment, says HCMA managing partner Darryl Condon, also in Vancouver, prompted the designers to ask, “Why don’t we just use wood? We were interested in wood as the primary element rather than a secondary element. To us, this treated the wood as having more authenticity and strength rather than it being subservient to steel.”
The result is the world’s longest-span timber-catenary roof, supported by what look like ribbons of Douglas fir stretching as long as 188 feet. The cables enable a remarkably thin roof that defines the 95,000-square-foot structure, which opened earlier this year and includes a 50-meter competition pool, waterslide, and a digital rain curtain.
In fact, the thinness of the roof system was more critical than its clear span. A deeper structural system, Condon says, increases the potential for corrosion and condensation buildup due to high humidity of natatoriums. For several years, HCMA—which has designed about a half-dozen of these difficult building types—experimented with thinner roof systems.
Ema Peter
Ema Peter
The center’s roof is just 18 inches deep, which includes the wood roof deck. (For comparison, the roof system of the nearby Richmond Oval, completed in 2008 and designed by CannonDesign, is about 8 feet deep.) Its slim profile reduces the building’s volume, eases maintenance, and eliminates the need for fire sprinklers in the bays between the glulam cables. Besides its maintenance benefits, a thinner roof is easier to sculpt, says Condon, who employed the catenary to express “a fluid form, something that would be reflective of the idea of water in motion.”
Having never used glulam as cables, HCMA worked closely with Vancouver-based structural engineering firm Fast + Epp, a longtime collaborator. The architects modeled the structure in Autodesk Revit, varying the height of the roof according to the building program: higher for the diving platforms and waterslide, lower for the entrance and changing areas. (The resulting cross slope also allowed the architects to channel rainwater efficiently to galvanized steel leaders along the north side of the building.)
Dozens of papier-mâché models followed, with HCMA settling on a sculpted roof form 380 feet long and 150 feet wide, interrupted only by the central concrete tower that divides the roof into a 188-foot span to the east, and a 120-foot span to the west. (The concrete supports at the building's ends and center make up the difference in total length.)
Ema Peter
Theoretically, that central pylon wasn’t necessary. According to Fast + Epp’s calculations, the timber cables could span the entire 300-foot building. The problem was vertical deflections. In the winter, heavy snow—though rare for the coastal city—might collect in the roof’s two concave bowls, weighing them down in the middle but pushing them up at the ends (similar to what happens when a person sits in a hammock or hops up on a slackline.) By adding the mid-span concrete support, deflections were limited to 8 inches, allowing HCMA to specify a glass curtainwall perimeter.
The final roof system is supported by more than 100 glulam cables, each 5 inches wide and 10 inches deep, coupled and anchored into the post-tensioned towers. Completing the roof are two roughly 0.5-inch plywood sheets, a vapor barrier, 4 inches of polyisocyanurate insulation, a 0.5-inch of gypsum board, and a single ply of TPO membrane.
Inside, pearl-colored Tectum panels are hung between the glulam cables, flush with the wood. By altering the length of the cables and the height of the bearing points (which range from more than 70 feet above finished floor to less than 30 feet), HCMA achieved its desired sculptural form using glulam cables with a single radius of 32 feet (down from more than a dozen in earlier iterations), lowering the cost of production significantly, Condon says.
Despite its unusual form, the roof was erected in just 12 days. The glulam cables, split into roughly 60-foot sections (for transportation purposes) were joined with a series of steel pins, whose holes were plugged with wood pegs, and lifted into place.
Goodbrand
The real challenge, Condon says, was getting the contractors and local code officials “to accept [an] unconventional structure,” even in progressive Surrey, the province’s second-largest city. “Whenever you try to do something different, you get a lot of resistance,” he says. “There’s a lot of inertia in conventional systems.”
But for a region still largely covered in forest, and where one in every 16 jobs is tied to the forest-products industry, Condon sees great potential in timber structures. He hopes the center will further demonstrate their potential. Architects “need to be more daring with wood,” he says. “We need to challenge ourselves and challenge the industry to push its limits.”
Timothy A. Schuler is a contributing editor at Landscape Architecture Magazineand writes about architecture, landscape architecture, and urban design for a variety of national and international publications. Based in Honolulu, he is a graduate of Kansas State University. Follow him on Twitter or visit timothyschuler.com.
For further information log on website :
http://www.architectmagazine.com/technology/detail/grandview-heights-aquatic-centres-timber-cables_o
aISISE, Department of Civil Engineer, University of Minho, Campus de Azurém, 4800-058 Guimaraes, Portugal
bEngineering Department – ECT, University of Trás-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real, Portugal
cIDMEC, Engineering Department - ECT, University of Trás-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real , Portugal
dOffshore Equipment Platform and Pipeline Maintenance Division, PTT Public Company Limited, 59 Moo 8 By-pass Road, Napa, Mueang, 20000 Chon Buri, Thailand
Received 29 September 2012. Revised 27 February 2013. Accepted 2 May 2013. Available online 22 July 2013.
Highlights
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Half-timbered walls represent a good seismic resistant solution typical of various countries.
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Traditional timber framed walls present high values of ductility, compared with other construction solutions.
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The wall’s behaviour depends on the connections, where the damage concentrates.
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One of the major influences of infill on timber-framed walls is the clear reduction of pinching.
Abstract The reconstruction of Downtown Lisbon after the 1755 earthquake was based on a novel constructive system of masonry buildings with an internal three-dimensional timber-framed structure named “gaiola pombalina”. This internal structure aimed at improving the global stability of masonry buildings, enhancing their capacity to dissipate energy under seismic loadings. But this structural system is not only typical of Portugal, but constitutes part of the built heritage of various countries. This paper aims at getting experimental insight on the mechanical behaviour of timber-framed walls subjected to in-plane loading, as only scarce information is available in literature, in order to assess their effective performance to seismic actions. To do this, the experimental results of cyclic tests carried out on traditional timber-framed walls with distinct typologies will be analysed, namely (1) unreinforced timber-framed walls without infill; (2) timber-framed walls without infill with Glass Fibre-Reinforced Polymer sheets (GFRP) placed at the connections; (3) timber-framed walls with brick masonry infill. Keywords
Timothy A. Schuler
