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Petronas Twin Towers

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Looking up at the Petronas Twin Towers
The Petronas Twin Towers are twin high rises located in Kuala Lumpur, Malaysia. They were designed by Argentinean-American architect Cesar Pelli and built by two separate construction consortiums headed by Hazama Corp. and Samsung Engineering and Construction between the years 1992 and 1997.

The Towers have 88 stories each and stand 1,483 feet (452 m) tall. The Council on Tall Buildings and Urban Habitat certified the Towers as the world’s tallest buildings in 1996, based on their structural top. They retained the title until 2004 when the Taipei 101 surpassed them.

The project cost US$1.8 billion to build.[1]

Tower One houses the Malaysian national oil company, Petronas, otherwise known as Petroleum Nasional Berhad. Tower Two is occupied by associate companies of Petronas, multinationals, and four restaurants. On the conjoined lower level, there is an 864-seat concert hall called Dewan Filharmonik Petronas.


[edit] Construction History

[edit] Symbol of Success

In the early 1990s, Malaysian prime minister Dr. Mahathir Mohamad wanted to create a structure that would represent the growing success of his country. In order to elicit ideas from the greatest architectural minds of the world, he developed an international contest. Renowned architect Cesar Pelli won the contest with his 88-story twin tower design, connected by a bridge. The bridge represented a gateway to the new Malaysia, a gateway to the future.

Cesar Pelli was the former Dean of Yale’s School of Architecture and had designed a number of prestigious buildings including Canary Warf in London, the World Financial Center in Manhattan, and Carnegie Hall Tower in New York.

Both towers standing tall

[edit] Architectural Design and Layout

Prime Minister Mahathir was impressed by Pelli’s initial concept, but felt the design was ultimately not Malaysian enough. He “wanted a building that would be identifiably Malaysian, that was of world class standard and which Malaysians could be proud of.”[2]

At first Pelli struggled to understand what it meant to be “uniquely Malaysian,” until he discovered that “Malaysian” meant Islamic. With this understanding he began studying all types of Islamic art, which condemns depictions of people, instead making use of geometric signs and symbols. However, Pelli was still unable to design a building the prime minister approved of.

Eventually Mahathir Mohamad understood what he wanted the towers to look like: an eight-pointed star, which in Islamic culture represents “unity, harmony, stability, and rationality.”[3]

However, Pelli was worried the new design limited floor space. He solved the problem by adding semicircles to each of the inner angles. Each tower would now have 43,600 square yards (36,455 m2) of floor space, including an additional circular annex standing 44 stories high. After eight months of designs, both parties were satisfied and the design was set.

“The building is rooted in tradition, but it is mostly about Malaysia’s aspiration and ambition,” said Pelli.[4]

The original proposed design was to be 1,400 feet (427 m) high, but when Dr. Mahathir realized, with a few adjustments, it could become the tallest building in the world, he pushed for the height to be raised in everyway possible. Many structural facts had to be recalculated and retested in wind tunnels. However increased height was achieved without adding any floors, but instead adding a small dome with an integrated pinnacle atop of the towers, reaching 1,483 feet (452 m) and surpassing the Sears Tower.

[edit] The Competing Companies

A project this big would usually require eight years, but the Malaysian budget only accounted for six. In order to meet the strict deadline, two construction consortiums were hired, one for each tower, racing each other to the top.

Tower One was built by a Mayjaus Joint-Venture led by Japan’s Hazama Corp. and made up of JA Jones Construction Co., MMC Engineering Services Sdn Bhd, Ho Hup Construction Co. Bhd and Mitsubishi Corp. The Tower One foreman was Robert Pratt.

Tower Two was built by a SKJ Joint-Venture led by Korea’s Samsung Engineering and Construction, and comprised of Kuk Dong Engineering and Construction Co. Ltd. and Syarikat Jasatera Sdn Bhd. The Tower Two foreman was Jon Dunsford.

[edit] Preparing the Foundation

The Petronas Twin Towers were going to be constructed on a former horse race track in Kuala Lumpur called Selangor Turf Club. However, it was soon discovered no proper survey of the site was ever done. So the companies began drilling boreholes searching for bedrock to support the towers.

“What we found was we were sitting not only on some decayed limestone, but we were sitting on the edge of a cliff,” said Pratt.[5]

Essentially, one side of the site was limestone, but the rest was soft brittle rock that would crumble under the pressure of the tower. So, structural engineer Charlie Thornton suggested moving the whole site about 200 feet (61 m), putting it entirely upon the soft ground. They would then have to drive piles deep into the earth to stabilize a concrete raft situated underneath the giant towers.

Excavation began in January 1993 to create “an underground ‘forest’ of columns made of concrete and steel.”[6] One hundred and four concrete piles, ranging from 200 to 375 feet (61 to 114 m) deep, were bored into the ground.[7] Then the concrete raft was poured in one continuous 54-hour period (one truck load every 2.5 minutes).[8] The concrete was poured continuously to ensure it dried evenly, otherwise the whole slab could crack.

Five hours into the pour, a heavy tropical storm hit the construction site forcing them to cover the concrete raft with canvas tarps while continuing to pour. The 54-hour pour was successful.

It held the world record for most concrete pour at one time.[9]

The raft was 15 feet (4.6 m) thick and weighed 32,500 tons.[10]

[edit] Race to the Top

The towers shining at night
The towers were constructed with more than 60 percent local materials including concrete, timber, marble, ceramic, tiles, and glass.

Construction of the towers began in April 1994 with Tower One starting a month earlier than Tower Two. The superstructure would be constructed of reinforced concrete instead of steel because Malaysia lacked a significant steel industry and importing it would be much too expensive. Also, “reinforced concrete has twice the ability of steel to withstand vibrations.”[11]

They enlisted the Chicago Testing Laboratory (CTL) to create an 80 grade concrete from materials local to Malaysia. The concrete had to withstand 20,000 pounds per square inch (137,895 kPa). After experimenting with different mixtures of gravel, water, and cement, they added silica, which reduced air bubbles in the concrete and increased its strength.

“The use of such high grade concrete was a transfer of technology from the USA, which uses up to grade 110 in the construction industry,” said Hahimah Hashim, the Kulala Lumpur City Center Bhd. general manager.[12]

The tower design called for 16 concrete pillars, each 19 feet (5.8 m) thick, to run up the length of the towers. Linked by a series of beams, the pillars could support 270,000 tons. Running up the center of the tower is a square core, which contains elevators, mechanical shafts, and other services.

Floors had to be constructed one at a time as the two companies raced towards the sky. In order to stay on budget each floor had to be constructed in four days; they were taking eight.

After a number of floors had been completed, a batch of concrete failed a routine strength test causing construction to come to a complete halt. Panic set in across the site wondering if any of the failed concrete had already been put into the towers. An inspector named Krish Krisnaswami come in to check how much, if any, of the “bad” concrete was already poured. He discovered one floor would have to be ripped up and redone.

As a result of the concrete failure, three separate concrete plants were set up on the site to ensure if one failed, two others would continue. Also, each batch would be tested before being poured into the towers. Every lost day cost US$ 700,000.[13]

However, the floor laying crew was also slowing construction down. As the most time consuming and labor intensive part of the project, flooring normally took 10 days per story to lay. The tower workers were able to reduce this time to four days, but the construction was still lagging way behind the deadline. The only way to finish on time was to make the site work 24 hours a day, seven days a week.

Still, the project soon faced another problem. Surveyors discovered that Tower One was an inch (2.54 cm) off vertical. So, to correct the problem, the next 16 floors were slanted back 0.08 of an inch (0.2 cm).[14] International specialist surveyors were then hired to check verticality every day and night.

By mid-1995, the project was 18 months from completion. In July 1995 they began lifting the skybridge into place.

[edit] Skybridge

The skybridge unites the two towers with a 192-foot (59-m), double-decker bridge. It connects at both the 41st and 42nd floors, and is supported by a three-hinged arch consisting of giant round bearings at the base and a pair of 167-foot (51-m) long legs. The base of the arch is located at the 29th floor. Both legs are bolted to a box girder below the center of the bridge.

The bridge is 558 feet (170 m) high and weighs 150 tons.

Inside one of the towers
Façade & Pinnacles

Cesar Pelli’s vision was for the towers to be a “multi-faceted diamond sparkling in the sun.”[15] Therefore the façade was constructed out of 16,700 square yards (13,963 m2) of stainless steel excursions. The steel reflects the luster of the tropical sun. The façade is also covered in 11,000 square yards (9,197 m2) of 0.8-inch (2-cm) laminated glass designed to reflect both ultraviolet and solar radiation. The outside curtain of the building was slotted together like a jigsaw puzzle, floor by floor.

The pinnacles that top both towers stand 241 feet (73.5 m) high. They consist of a spire, mast ball and ring ball. They are also equipped with aircraft warning lights and window washing equipment. Each one took more than 19 weeks to make. One was made in Japan while the other was built in Korea.

[edit] Elevators

With approximately 10,000 people using the towers every day, mobility was extremely important.[16] The elevators were manufactured by Otis Elevator Co.

Each tower is equipped with 29 double deck lifts, six service lifts, and four executive lifts. The double deck lifts can carry 26 people per deck—52 total—and can reach speeds of 20 feet (6.1 m) per second.

The executive lifts can carry 10 people.

[edit] Equipment Used

[edit] References

  1. Malaysian Culture Group. The Twin Towers with a View, January, 2005. (accessed: 2008-09-23)
  2. Yang, Lee Yang. Petronas Towers: In Detail. Architecture Enlightens Life, April 2008. (accessed: 2008-09-23)
  3. Yang, Lee Yang. Petronas Towers: In Detail. Architecture Enlightens Life, April 2008. (accessed: 2008-09-23)
  4. Official Petronas Twin Towers website], 2008-09-23.
  5. National Geographic. Megastructures: Petronas Twin Towers
  6. Design and construction of Petronas Towers, July, 2007. (accessed: 2008-09-23).
  7. Malaysian Culture Group. The Twin Towers with a View, January, 2005. (accessed: 2008-09-23)
  8. National Geographic. Megastructures: Petronas Twin Towers
  9. National Geographic. Megastructures: Petronas Twin Towers
  10. Petronas Towers, 2008-09-23.
  11. Yang, Lee Yang. Petronas Towers: In Detail. Architecture Enlightens Life, April 2008. (accessed: 2008-09-23)
  12. Petronas Twin Towers: The Tallest Buildings in the World, 2008-09-23.
  13. National Geographic. Megastructures: Petronas Twin Towers
  14. National Geographic. Megastructures: Petronas Twin Towers
  15. Yang, Lee Yang. Petronas Towers: In Detail. Architecture Enlightens Life, April 2008. (accessed: 2008-09-23)
  16. National Geographic. Megastructures: Petronas Twin Towers