Archive for August 9th, 2010

August 9, 2010

Santa Monica introduces ‘sharrows’ on 14th Street

‘Sharrows,’ or ‘shared lane arrows,’ are one of the elements of a larger bike plan that Santa Monica is developing, said a senior transportation planner.

Sharing lanes

Anthony Gianatasio rides near the newly painted “sharrows” on Santa Monica’s 14th Street.(Lawrence K. Ho, Los Angeles Times / June 29, 2010)

By Martha Groves, Los Angeles Times

July 4, 2010

icyclist Anthony Gianatasio has had many a memorable scrape with motorized vehicles over the years, as the scars on his arms, legs and face attest. Drivers have thrown things, gestured impolitely and shouted at him to move to the &*%@!* sidewalk.

As a result, Gianatasio welcomes the new “sharrows,” or “shared lane arrows,” that the city of Santa Monica has applied to a freshly paved section of 14th Street between Washington and Montana avenues.

“It’s a big relief,” Gianatasio, 39, said of the symbols, which feature a pictogram of a bicycle beneath two chevrons. The markings, which resemble those seen throughout some European cities, are intended to remind motorists that they are legally obligated to share the road.

“As cyclists, we can’t educate the motorists,” Gianatasio said. “When the city paints these markings, it goes a long way.”

With its first “sharrows,” Santa Monica joins a number of other U.S. cities attempting to make it easier for cyclist and motorist road warriors to coexist. Denver and San Francisco were among the earliest proponents to use the markings, but Los Angeles, Long Beach and other cities have also begun adopting them.

“They’re sort of popping up all around the L.A. area,” said Aurisha Smolarski, a spokeswoman for the Los Angeles County Bicycle Coalition.

The markings do not connote a separate bicycle lane per se but rather guide cyclists to travel outside the dreaded “car door zone” — the area of vulnerability where many cyclists have been “doored” by inattentive drivers climbing out of their vehicles.

Sharrows are one of many elements of a bike plan that Santa Monica will put together once a new development and traffic plan, now in draft form, has been adopted, said Michelle Glickert, senior transportation planner with the city. Other options, she said, will be bike lanes and bike boulevards, which would feature a painted biker and the word “boulevard” along with signage.

“Cyclists need safe, comfortable and convenient access to all streets,” said Matt Benjamin, senior associate with Alta Planning + Design, a consulting firm. “In some cases it will make sense to favor bike capacity over auto capacity, but in other cases peaceful coexistence may be the best option. That’s where shared lane markings are useful.”

Cyclist Marc Thomas, 46, who watched the new markings go in on 14th Street, said he now uses the road as his regular route to his favorite coffee place on Montana Avenue. “It’s beautiful,” he said. “You feel like you’re at home. It gives the impression that cyclists and walkers and drivers all need to and should get along well.”

The sharrows encourage cyclists to ride further to the left in the travel lane, something they are legally allowed to do even if it means blocking the lane at times. Gianatasio experienced the soothing effects one recent afternoon. Drivers following him gave him plenty of space and a wide berth as they passed.

The Los Angeles Department of Transportation was recently criticized by cycling blogger Stephen Box, who said in a SoapBoxLA posting that engineers in late June had incorrectly placed some sharrows on Fountain Avenue. By his calculations, Box said, the markings steer cyclists too close to the door zone and encourage motorists to ride side by side with cyclists, even though the road is too narrow.

“All that money spent on research and planning and preparation and implementation and yet the LADOT Bikeways failed to accomplish the three goals of a sharrow,” he wrote. Those goals, he said, are to get cyclists out of the door zone, position cyclists in the center of a non-sharable lane and communicate clearly to motorists the correct position of a cyclist on a narrow lane.

In Santa Monica, Gianatasio has no complaints. With the sharrows in place, he said, “I’ll actually take my children down 14th Street.”

martha.groves@latimes.com

http://www.latimes.com/news/local/la-me-sharrows-20100704,0,7387057.story

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August 9, 2010

Shifting up a gear

Rent-a-bike projects are cropping up in unlikely places

Jul 15th 2010 | MEXICO CITY

THIN air, thick smog and bad drivers make Mexico City hard going for cyclists. But a new fleet of 1,200 smart red “Ecobici” pay-as-you-go rental bikes, at 85 docking stations, marks the most ambitious recent addition to a global trend of municipally endorsed cycling. Since February 7,000 people have signed up, and between them they have taken more than 200,000 trips.

A low-tech scheme started in the French town of La Rochelle in 1974. Copenhagen launched the first big automated project in 1995. German cities, including Berlin, have tried versions paid for by mobile phone. But the most successful is the “Vélib” in Paris, with 20,000 bikes available for users with swipe-cards. In London the transport authority and Barclays Bank will launch a 6,000-bike programme on July 30th. Users can pay at one of the 400 docking stations, or use a key with a chip.

Life in the slow lane

The vulnerability for most schemes is theft. Thousands of the Parisian bikes disappeared in the scheme’s early stages, turning up as far afield as Romania and Morocco. Portable locks have proved a weak point: the mandatory use of docking stations is more secure. “We were expecting people to steal them, but that hasn’t happened,” says Marcelo Ebrard, Mexico City’s mayor. Only one of the 1,200 bikes in the scheme has gone missing to date.

The paradox of urban cycling is that bad traffic is both deterrent and incentive. When demonstrations or traffic-signal failures bring Mexico’s streets to gridlock, businessmen can be seen strapping their briefcases onto Ecobicis.

Cyclists in places like London and Mexico City yearn for proper cycle lanes, of the kind commonplace in countries such as Germany. A second-best solution is the right to ride (gently) through parks and on pavements without being fined. On that score at least Mexico’s traffic police, the scourge of motorists, are charm itself.

For now, the hope is that new bike-hire schemes help raise cyclists’ numbers enough to change motorists’ behaviour—and thus erode the perception of danger that keeps people off their bikes.

http://www.economist.com/node/16591116?story_id=16591116&fsrc=scn/tw/te/rss/pe

August 9, 2010

Cycling Copenhagen, Through North American Eyes

by Clarence Eckerson, Jr.

While Streetfilms was in Copenhagen for the Velo-City 2010 conference, of course we wanted to showcase its biking greatness.  But we were also looking to take a different perspective then all the myriad other videos out there.  Since there were an abundance of advocates, planners, and city transportation officials attending from the U.S. and Canada, we thought it’d be awesome to get their reactions to the city’s built environment and compare to bicycling conditions in their own cities.

If you’ve never seen footage of the Copenhagen people riding bikes during rush hour – get ready – it’s quite a site, as nearly 38% of all transportation trips in Copenhagen are done by bike.  With plenty of safe, bicycle infrastructure (including hundreds of miles of physically separated cycletracks) its no wonder that you see all kinds of people on bikes everywhere.  55% of all riders are female, and you see kids as young as 3 or 4 riding with packs of adults.

Much thanks to the nearly two dozen folks who talked to us for this piece.  You’ll hear astute reflections from folks like Jeff Mapes (author of “Pedaling Revolution“), Martha Roskowski (Program Manager, GO Boulder), Andy Clarke (President,League of American Bicyclists), Andy Thornley (Program Director, San Francisco Bike Coalition) and Tim Blumenthal (President, Bikes Belong) and Yvonne Bambrick (Executive Director, Toronto’s Cyclists Union) just to name drop a few of the megastars.

http://www.streetfilms.org/cycling-copenhagen-through-north-american-eyes/

August 9, 2010

McDonalds Cycle Center at Millennium Park / Muller&Muller

Architect: Muller&Muller, Ltd
Location: Chicago, IL, USA
Client: City of Chicago Department of Transportation
Program : parking for 300 bikes / bike repair and parts shop / showers and lockers / Chicago bicycle police station / portable cafe / bike rental
Project Area: 1,486 sqm
Budget: US $3,000,000
Photographs: Nathan Kirkman & Robert Murphy

park-elevation

This project was constructed on three levels on top of and below the northwest corner of Chicago’s Millennium Park. The facility includes secure storage space for 300 bicycles, individual day use lockers, private shower stalls, and a bike repair area. The purpose of the new facility is to encourage and promote commuter bicycle transit into downtown Chicago. The building also houses the Chicago lakefront bicycle patrol and rents bikes for hourly use.

A glass-enclosed atrium links the two upper levels and gives a street presence to the mostly below- grade facility. The atrium, though small, provides a grand entry for the building. Its shell is designed to be energy efficient, incorporating natural ventilation, visible rooftop photo voltaic panels, and wall shading devices composed of fabric awnings and climbing plant material. The bike station has been constructed within the constraints of an existing parking garage structure which forms the base of Millennium Park. Interior bike station spaces are designed to maximize the limited headroom provided by this garage structure. Much of the space is below grade so lighting, colors and materials were chosen to provide a bright playful contemporary space avoiding the oppressive sense of being underground. The multiple levels of the project site also presented the problem of moving bikes up and down. This obstacle was overcome by incorporating gentle ramps into the edges of low incline stairs.

Plazas were added at two levels to accommodate retail /cafe functions and overflow bike parking for special events. The atrium structure was designed with an outer shell of stainless steel cables on which climbing plants will grow. Once mature, the plants will provide sun shading in the summer and will drop their leaves in winter to allow in the warming sun. The outer layers of the skin are created with combinations of loose planes floating around the inner, more solid shell. The building dissolves as it moves outward. Plants growing on the building are treated like building materials. They will be tightly cropped into solid mats of growth taking on geometric architectural forms allowing the building to change its appearance over time. Vines grow to cover more of the building, flowers bloom and recede, and leaves drop revealing the building’s structure. The Bike Station becomes part of the park by using the park’s own material as its cladding.

atrium-racks

bathing

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canopy-detail

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millennium-park

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showers

site-plan4 site plan

main-plan floor plan

general-section general section

summer-section summer section

winter-sect8ion winter section

http://www.archdaily.com/31324/mcdonalds-cycle-center-at-millennium-park-mullermuller/

August 9, 2010

Reflective giants: Chicago’s building boom, now nearing its end, has layered a new generation of glass towers into the skyline

Legacy

Chicago’s renowned skyline has long been about muscle, its towers as solid as a meat cutter at the old Stockyards.

But now, with the decade-long building boom coming to a close, a little-noticed change has come into focus: A new family of skyscrapers, principally sheathed in light-catching glass and at least 50 stories tall, has quietly infiltrated the skyline. And this invasion is by and large a good thing, giving us buildings notable not simply for their shapes, but for their lightness, transparency and reflectivity.

Let’s call them the “glass giants.” And here’s what they add up to: Even though the tallest tower proposed during the boom — the corkscrewing, 2,000-foot Chicago Spire — shows no signs of being built, the skyline has continued to evolve, and in a way that is unmistakably, if not always satisfyingly, of its time.

With its shimmering, ever-changing exterior wall of reflective glass and stainless steel fins, Donald Trump’s year-old, 96-story riverfront hotel and condo tower is the biggest of the giants. Yet there are others, including two condo towers that are now open — the 73-story Legacy at Millennium Park (left), an elegant wedge that overlooks its namesake park, and the 57-story One Museum Park West, a carefully modeled high-rise on Grant Park’s south end.

Northend2

Others (left) include the ruggedly handsome 54-story Blue Cross-Blue Shield of Illinois headquarters at 300 E. Randolph St., an add-on building whose second phase took shape last year, and just to its east, the context-sensitive, 64-story 340 on the Park condo tower, now three years old.

It is always dangerous to evaluate buildings as a group, but this group nonetheless shares certain characteristics.

The new towers both reflect the sky and seem to blend into it, minimizing (though not necessarily masking) their enormous bulk. Their lightness enables them to soar above revered landmarks — the Wrigley Building and the clifflike wall of high-rises that lines Michigan Avenue — without overwhelming them. And those along Grant Park are good neighbors in another way, creating a sharply defined urban “edge” on the park’s previously ill-defined north and south flanks.

Yet the glass giants perhaps look best when one surveys the skyline and recognizes what they aren’t — nostalgic stage sets like the 60-story Elysian, a concrete-faced hotel-condo tower at 11 E. Walton St. that flaunts an oversize mansard roof resembling a Shriner’s fez. If the towers had turned out that way, a skyline synonymous with modernity would be weighted down with ponderous “mansions in the sky” — a bloated version of Paris.

To be sure, high-rises chiefly clad in glass have appeared before on the Chicago skyline, most winningly at 333 W. Wacker Drive, the office building whose gracefully curving, green glass wall reflects a bend in the Chicago River. But the glass giants are taller and more prominent than the 36-story 333 Wacker, their visibility from Grant Park magnifying their skyline presence. In addition, the glass giants are lighter and more transparent that the steel and glass boxes of the 1960s, whose dark surfaces and projecting I-beams convey a palpable solidity.

Because architecture is the most pragmatic of the arts, it should surprise no one that the reasons for the shift to glass begin not with aesthetics but economics. More glass makes for better views, and jaw-dropping vistas sell real estate, particularly in tall buildings.

Trump

“Clients are asking for more visibility from the spaces within,” said Adrian Smith, the former Skidmore, Owings & Merrill partner who was the lead designer on Trump Tower (left) and now has his own firm.

Other factors have contributed to the shift. Glass surfaces are easier to maintain than stone, and they are generally lighter and less expensive, Smith said. Stricter energy codes, like the one Chicago passed in 2002, have encouraged builders to sheathe their buildings in materials including glass to improve insulation. Superthin coatings allow windows to filter out solar heat without obstructing views from the inside out.

The recent ascent of modernism and the changing nature of high-rises have also played roles. Because so many of the new towers are residential, with irregularly spaced columns carving out extra-large living spaces, architects have further reason to shy away from the rigid, structurally expressive look that long ago went out of fashion.

In short, the glass giants are more skin buildings than bone buildings, the latter exemplified by the X-braced muscle of the John Hancock Center.

All of these changes are evident in the Legacy at Millennium Park, which was designed by Chicago architects Solomon Cordwell Buenz and soars nearly 820 feet into the air — high enough to make it the tallest building in such large American cities as Miami or Minneapolis.

Five years ago, Solomon Cordwell Buenz had just finished the postmodern Heritage at Millennium Park, a solid but not particularly innovative 59-story, exposed-concrete condo tower that rises two blocks north of the Legacy. The new tower shows how much things have changed since then, even if it is by no means a perfect building.

The Legacy has been shoehorned into a tight site between the row of officially protected landmarks on Michigan Avenue and the elevated tracks on Wabash Avenue. To make room for its base, the tower’s developers sheared off everything but the facades of three historic commercial buildings on Wabash — another one of those lamentable “facade-echtomies” that preserves a streetscape but destroys architectural integrity.

Legacy2

But on the skyline, the Legacy excels.

In contrast to the modernist hulk at 55 E. Monroe St., which shows Millennium Park the broad side of its massive slab, the wedge-shaped Legacy turns its narrow front toward the Crown Fountain and Cloud Gate. Two adjoining slabs rise alongside each other, separated by a stack of recessed balconies. One slab is slightly taller than the other, and its top tilts slightly, introducing a subtle geometric counterpoint.

The design is emphatically vertical, yet the tower’s softly reflective, minimalist skin of light-blue glass effectively pushes the “mute” button, tempering its geometric complexity. The simple surfaces transform the Legacy into a quiet mirror as it rises behind the Gothic filigree of the adjoining University Club and the broochlike ornament of Louis Sullivan’s Gage Building at 18 S. Michigan Ave.

Though the Trump Tower has more articulated skin than the Legacy, it plays the same game as it soars above the Spanish Revival Wrigley Building and the neo-Gothic Tribune Tower. It is at once a skyline object and a background building, a luminous presence that contrasts vividly with the decorative but opaque surfaces of the 1920s towers. It’s a thrill to watch the building’s blue skin turn white as the setting sun reflects off its fins of stainless steel. Such qualities compensate for the tower’s subpar spire and riverfront bulk.

The glass giants “are a real complement to the skyline,” said Pauline Saliga, executive director of the Chicago-based Society of Architectural Historians and the editor of “The Sky’s The Limit: A Century of Chicago Skyscrapers.” “Their light, reflective qualities make them beautiful rather than ponderous and heavy.”

Pappageorge

The glass giants lining the north and south flanks of Grant Park reveal the positive urban impact of this trend. In contrast to the steel-and-glass high-rises of the 1960s, many of which stood aloof on windswept plazas, the new towers appropriately treat the park as if it were an outdoor room and they were the walls enclosing its vast open space. One Museum Park West, a westward addition to the bold but cartoonish, 66-story One Museum Park East, is a good example.

Its architects, the Chicago firm of Pappageorge Haymes, had previously turned out desultory concrete towers along South Lake Shore Drive that aped the robust classicism of the neighboring Museum Campus.
But clients began asking, the architects say, for modernist towers with floor-to-ceiling glass instead of traditional ones whose small windows left room for art on the walls. More important, planners at City Hall started preaching the gospel of tall, thin towers that would be arranged with an eye toward urban design, not just view corridors that would line developers’ pockets.

As at the Legacy, there are problems — but only more so. The nautically inspired One Museum Park East, the least persuasive of the glass giants, looks painfully pudgy from Lake Shore Drive. One Museum Park West’s top is disappointingly blunt compared with the exuberant, nautilus-shaped crown that Pappageorge Haymes planned. Yet these towers still improve on the architects’ previous efforts, especially as works of urban design.

Pappageorge2

The towers’ great height gives them enough visual oomph to match the row of tall buildings on the park’s northern edge. Pappageorge Haymes carefully placed them side by side, joining them at the bottom but leaving a slot of open space between them. The bands of metal that sweep across their glass facades appropriately suggest a single, continuous wall, which has been cleaved in two.

Thus, while the boldly scalloped skyscrapers are aligned to capture views and sell condos, they now serve the broader civic agenda of shaping the public realm. And their glass walls, while hardly jewel-like, captivatingly capture the light.

How architectural historians will eventually rate the glass giants remains a matter of speculation. There are surely no masterpieces among the group — nothing that possesses the modernist brio of the Hancock Center or the Art Deco elegance of the Chicago Board of Trade Building. Some are clearly more satisfying than others. Yet on the whole, these exercises in lightness and luminosity merit praise for the way they enliven the skyline and uplift the cityscape.

By Blair Kamin

http://featuresblogs.chicagotribune.com/theskyline/2010/08/chicagos-renowned-skyline-has-long-been-about-muscle-its-towers-as-solid-as-a-meat-cutter-at-the-old-stockyards–but-now.html

August 9, 2010

Beyond Limits

The Burj Khalifa’s designers tackle extreme height and extreme climate to create a landmark for the 21st century.

By Josephine Minutillo

Skeptics question the logic behind building a supertall skyscraper in the middle of the desert. Others are less interested in why the Burj Khalifa exists than how it was built. The secrets to its construction might surprise you. While the Dubai landmark dwarfs its closest rival in the competition for world’s tallest building by more than 1,000 feet, it doesn’t flaunt its architectural muscle. Rather, its design is as straightforward and logical as it gets.

At the heart of that logic is the building’s triaxial geometry. “The Y-shaped plan is ideal for a residential building because it gives plenty of surface area per unit, and structurally, it is much better than a cruciform or linear tower,” explains Adrian Smith, FAIA, former design partner at Skidmore, Owings & Merrill (SOM) in charge of the project through the completion of construction documents. And though SOM’s competition-winning design for the Burj far exceeded the approximately 550-meter (1,800 foot) height called for in the brief to make it the world’s tallest, the scheme — originally at about 700 meters, or 2,300 feet — was selected based on its appearance and construction feasibility, according to Smith.

The center of the structural-concrete tower features a hexagonal core that surrounds the elevators. Since the core is not big enough to rise to such extreme heights on its own, it is buttressed by the three wings. While the core functions as an axle to keep the building from twisting, 2-foot-thick corridor walls on either side of each wing act like the web of an I-beam; cross walls like the flanges. Round columns are located at the pointed end of each wing between ordinary flat plate slabs. The result is a tower that is extremely stiff laterally and torsionally.

The Burj Khalifa’s organic form has a triaxial geometry. The Y-shaped building’s three wings are connected to a central core. As the tower rises, one wing at each tier sets back in a spiraling pattern.

Photo: EMMAR

“These are very conventional systems, just arranged in a unique manner,” says William Baker, structural engineer partner at SOM. The driving force behind the structural design was wind. “Tall building design is dominated by wind forces, even in most seismic areas where earthquakes are a major concern,” Baker says. Since wind velocities increase with height, it was an even greater concern here. Consulting engineers Rowan Williams Davies and Irwin (RWDI) carried out extensive wind-tunnel testing over the course of two years in its renowned facilities in Ontario, Canada. First, balsa wood models of the slender tower were subjected to force balance tests. Later, more sophisticated aeroelastic tests were conducted. RWDI studied the building’s six important wind directions — the pointed end, or nose, of each of the three wings, and the areas between two wings, called tails.

The most significant change to come from RWDI’s analysis did not significantly affect the building’s design but rather its orientation. Since analysis indicated less excitation in wind patterns blowing at the nose, the tower was rotated 120 degrees from its original position so that the noses faced into the wind. RWDI also suggested that the Burj’s different tiers be made more regular. “Initially, the building spiraled much more dramatically,” says Smith. “But each time it steps back, it changes how the wind reacts. To keep the wind from organizing into vortices, we evened out the setbacks.”

While changes to the design were being made, so too were changes to the building’s use. Originally meant to be all residential, the client, Dubai-based Emaar Properties, added offices to the program. Corporate suites were located at the top of the tower, which, with floor areas as low as 5,000 square feet, is more ideally suited for apartments, the original intent for those floors. But the program was not the only element to be in flux. The tower’s final height remained a question mark until rather late in the game. It wasn’t until after the foundation was in place and construction of the superstructure began that the magic number — 828 meters, or 2,717 feet — was finally determined. “I hated the proportions of the shorter tower and kept pushing for it to be taller,” recalls Smith. The economy was on Smith’s side at that point, and the client agreed it looked better taller.

The tower’s strategic design allowed flexibility in terms of changes in program and height. The addition of offices required an extra set of elevators, which were accommodated in one of the wings. The other two wings would then house elevators for the apartments and hotel, respectively. Issues of proportion and scale were paramount in the Burj Khalifa’s design. Unlike the Willis (formerly Sears) Tower, which scales by the cube, the Burj scales by the square. So whereas doubling the height of the Willis Tower would increase its area eightfold, doubling the height of the Burj only increases its area fourfold; its wings would get longer but not wider.

Nevertheless, most of the extra height was in the spire, which Baker calls “a nest of steel triangles that sits on the hexagonal walls.” At the opposite end, at the very bottom of the building, a 12-foot-thick concrete mat, or raft, foundation rests on the surface of a calcisiltite rock mass. It was constructed in four separate pours — one for each of the three wings and the center core. Then, 194 5-foot-diameter piles were driven 140 feet below the mat. Most of the piles are located toward the edge of the mat, with very few at the center. “It’s all about decreasing wind forces and managing gravity,” says Baker. “By the time you get to the bottom, everything is in compression, so you don’t need much reinforcing. The reinforcing there is similar to what you’d see in an average 20-story building. We’re very proud of that.”

None of this would have been possible without recent material advancements. “We discovered this new material called concrete,” Baker jokes. “It is so different from the stuff we used to call concrete.” While in the past, slump tests were used to measure how hard and consistent a sample of concrete was, the chemicals in the ultra-high-performance concrete used for the Burj make it so flowable that it forms a puddle. (Silica fume and fly ash are its main ingredients.) The quality control comes in measuring the diameter of the puddle.

Regardless of the concrete’s 100 MPa (14,500 psi) strength, all concrete changes dimension over time. Fifteen separate three-dimensional finite-element analysis models predicted the effects of creep, shrinkage, and foundation settlement. “We made precise calculations with data that is very rough,” says Baker. “It’s all going to shrink. The problem comes when one part moves differently from another.”

The key to minimizing that kind of differential movement was to use the same concrete in every vertical element, and to ensure that columns and walls had similar volume-to-surface ratios so that they dried at the same rate. There are virtually no transfers within the concrete structure. Designers adhered to a strict 9-meter (29.5 foot) module. Where a wing sets back and the columns at its nose drop off, the next set of columns appears directly over the walls beneath it.

“You verify as much as possible through computer programs and calculations, but it’s not an easy thing,” Baker admits. “In the end, you walk the building and look for cracks.” So far, the building has settled about 2 inches.

Samsung Corporation was responsible for making the design a reality. The Seoul-based contractor used an automated self-climbing formwork system to build the concrete structure. Specially developed pumps brought the concrete to heights of 600 meters (1,970 feet). The structural steel spire was constructed from inside the building and jacked to its full height of over 200 meters, or approximately 700 feet, using a hydraulic pump.

Structural concrete gives way to steel at the tower’s top section, where a structural-steel spire utilizes a diagonally braced lateral system.

Photo © Samar Jodha/Spectra Maxima

Seven two- to three-story-high mechanical floors are distributed throughout the building, about every 30 floors or so. “It’s really a series of 30-story buildings stacked on top of one another,” Baker says. “There would be too much pressure in the pipes, and ducts would get too big, if you try to move things too far.”

The mechanical floors house various equipment, including water tanks and pumps, air-handling units, and electrical substations. Track-mounted building-maintenance units, used for window washing, are stored in garages within the structure. “We were very aware of the sand problem,” Smith says. “The consistency of the sand in Dubai is more like talcum powder. It sticks to everything.” The building was kept as flush as possible, and ledges were kept to a minimum to reduce the number of areas where sand could settle. Window washing is expected to take place every few months.

Over 26,000 low-E, antiglare glass panels were used in the exterior cladding of Burj Khalifa, which features more than 1.8 million square feet of glass. Eight-inch-long wing-shaped, stainless-steel mullions occur at every glass joint. “We originally designed the exterior wall with steel tubes, but it looked too industrial,” recalls Smith. “The sheen of the vertical stainless steel, especially in the horizontal sun of morning and evening, makes the building sing.”

Curtain-Wall Detail

1 aluminum vertical mullion
2 clear reflective insulating vision glass
3 stainless-steel vertical fin
4 horizontal spandrel panel
5 concrete slab

The tower used over 430,000 cubic yards of concrete and 43,000 tons of steel rebar. To help determine the concrete-to-rebar ratio, three-dimensional finite-element analysis models were used to predict the effects of creep and shrinkage.

Photo © Samar Jodha/Spectra Maxima

While the building’s structure and its exterior, including the cladding, were designed to resist a variety of forces, forces of a different kind needed to be addressed inside the tower. According to SOM’s Luke Leung, “There is a tremendous amount of pressure in a building of this height, both on the water side and on the air side.”

The typical system pressure for water is 300 psi. The Burj has one of the highest water pressures in the world at up to 460 psi. “Imagine a water pipe that is 800 meters tall,” says Leung. “You don’t want to be standing under that.”

Pressure breaks are typically added in high-rise buildings to alleviate the forces. In the Burj, SOM created some of the highest pressure breaks ever in a building, consisting mainly of heat exchangers to isolate one riser from another. The tower’s water system supplies an average of 250,000 gallons of water daily.

Cooling the water presented another challenge for SOM’s engineers. “When we first started coming to Dubai, we noticed that the hot water in our hotels was very hot, and that the cold water was also very hot,” says Leung. “Imagine getting hot water out of the cold faucet at the Armani Hotel!”

Since Dubai has limited fresh water and relies on the sea, the water had to travel through the very hot ground during the salt evaporation process. Instead of following that scenario, SOM took advantage of the area’s high humidity and the large amount of condensation that results. “The moisture is so high that if you collect condensate in the air during a cooling period, you get a significant amount of water in the 55—65 degree Fahrenheit range,” explains Leung. This water is collected and drained in a separate piping system to a holding tank. The system provides about 15 million gallons of supplemental water per year. A sitewide graywater collection system collects water for use in landscape irrigation.

The effects of air pressure are more noticeable to the average visitor to the Burj. There is an enormous amount of air movement going through the building. Due to Dubai’s high temperatures, reaching 115 degrees Fahrenheit and higher in the summers, the stack effect is reversed. Instead of hot air rising, it is sucked in from the top of the building and directed downward because the inside of the building is cooler than the outside.

Stack effect is a function of both the building’s height and the temperature difference between the inside and the outside. Both are extreme in this case. When you enter the building in the heat of summer, the air will feel like it is trying to push you out. “In Chicago, for instance, it is 75 degrees inside and as high as 95 degrees outside on a summer day,” Leung explains. “In Dubai, the temperature difference in summer can be more than 40 degrees Fahrenheit.”

What is not so apparent from the building’s height is the amount of power it consumes. As electricity travels through the building, which in essence is a stack of five 30-story buildings, it loses voltage similar to the way water loses pressure flowing through a small pipe. To supply these massive loads efficiently, the Burj’s electrical mains are supplied with 11 kV, 23 times higher than the 480V typically used in the U.S. Transformers located at each of the mechanical levels reduce the voltage to intermediate levels for heavy equipment and to 220V, the normal voltage used in the U.A.E., for office equipment and appliances.

Fire-and life-safety issues are a vital concern in high-rise buildings, particularly one of unprecedented height such as this. The Burj contains 57 elevators, some of the fastest in the world, serving different building zones, though no one elevator travels more than 500 meters (1,640 feet). According to Baker, the longest elevator ride takes under two minutes — with the express elevator to the observation deck on level 124 taking much less time. Baker also admits to walking down the full height of the building (at a leisurely pace) in about 45 minutes. A typical floor contains three sets of concrete-encased fire stairs, one in each wing.

In case of fire emergency, the building deploys a “defend in place” strategy. Fire-rated, air- conditioned refuge areas accommodate building occupants until further instruction. Some elevators are equipped with cameras so that elevator shafts can be inspected remotely.

Despite the challenges involved in designing the Burj Khalifa, and the criticisms leveled against it in the wake of Dubai’s subsequent financial meltdown, Adrian Smith staunchly defends it. “The Burj was an important piece for Dubai at the time it was built,” says Smith. “Dubai wanted to be recognized as an international player on par with other major world cities, and it needed an international landmark to do that.”

Originally published in the August 2010 issue of Architectural Record

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