Archive for March, 2010

The construction of the PETRONAS Towers was a model of cooperation and efficiency and in some respects even more spectacular than the final result.

After a year of planning, the construction phase began in March 1993 with the excavation work for the foundation. The originally selected location was moved 60 meters due to the configuration of the bedrock exposed during the excavations. The excavation for the foundation went 30 meters below the soil surface, with work proceeding only after sunset and more than five hundred dump trucks full of soil being removed from the site each night.

For each of the two towers, more than one hundred foundation piles were poured next. Once the forms were in place, the slabs for the foundation of the two towers were poured in two continuous pours lasting about two and a half days each and using over 13,000 cubic feet of concrete for each of the two slabs. On top of these slabs a perimeter wall over a kilometer in total length and 21 meters tall was created to form the shell that would become the five-level underground car park.

The contract to construct the two towers was given to two different contracting companies and their friendly competition resulted in both remarkable speed and valuable cooperation as each team shared with the other information gained during the building process.

Tower One, which houses the PETRONAS headquarters, was built by a group led by the Japanese Hazama Corporation along with J.A Jones Construction of Charlotte North Carolina, and the Mitsubishi Corporation, MMC Engineering, and Ho Hop Construction of Japan.

Tower Two was constructed by the SKJ Consortium, composed of Samsung Engineering & Construction and Kuku Dong Engineering & Construction from Korea, Dragages and Bachy-Soletanche from Singapore and Syarikat Jasatera and First Nationwide Engineering Sdn Bhd from Malaysia.

Work on the tower structures started in April 1994 was completed by June 1996, with the first tenants moving into the buildings in 1998. The Malaysian Prime Minister Mahathir bin Mohammad presided over the opening ceremonies for the towers on Aug. 31, 1999, which coincided with the celebration of Malaysia’s Hari Kebangsaan holiday that marks the unification of the country and the establishment of the Malaya Federation in 1957.

Although many foreign firms participated in the construction process, a great deal of the work was done by local Malaysian companies. It is estimated that sixty percent of the materials used in the construction were obtained locally. All of the concrete and construction timber was Malaysian in origin as were many of the interior finishing materials including marble, ceramic tiles, and drywall materials. Many of the more complex features such as escalators, electrical fixtures and components and furniture were also supplied by Malaysian firms.

The functional structures of the PETRONAS Towers were designed by the structural engineers Thornton-Tomasetti, with headquarters in New York, and Ranill-Berskutu of Malaysia. The core structure of each of the towers is composed of a ring of sixteen cylindrical columns of high strength reinforced concrete. The columns vary in size from 2.4 meters in diameter at the lower areas to 1.2 meters in diameter at the top, and are placed at the outside corners and additional arcs of the eight pointed star shape that gives the buildings their classic Islamic shape. In a staging of six increments, the columns slope slightly inward as they rise, resulting in the tapered form of the final buildings. The columns are linked with a series of concrete core walls and ring beams and the architect César Pelli has described these movement-resistant and damper-free structures as a pair of “soft tubes”. There are actually two concentric pressurized cores in the structures, and the two cores unite at the 38th floor of each tower.

A significant choice of building materials was made early in the project, and it was decided to use reinforced concrete instead of the structural steel that is more common in other skyscrapers. This choice was made not only because local Malaysian contractors were more experienced building with concrete than with steel, but also because the cost of importing all the steel would have been prohibitive, whereas the concrete could be obtained locally. The final towers weigh more than twice what they would have had steel been used, but it was additionally felt that the use of concrete would more effectively dampen sway in windy conditions and reduce vibrations within the towers.

The structural plan liberates additional floor space inside the towers by locating the mechanical services for the towers in two “bustles” that are 43 story tall buildings located immediately adjacent to the towers. After completion, the exteriors of the two concrete “soft tubes” were clad in stainless steel and glass with a design that originated in the classic geometric patterns of ancient Islamic art. The foundations for the structures are huge concrete cores and are considered the deepest building foundations in the world.

The two 73-meter tall pinnacle structures of the towers were, like the towers, constructed by two different contractors. One of the pinnacles was fabricated in Japan and the other in Korea. Built of structural steel and then disassembled and shipped to Kuala Lumpur, the pinnacles were reassembled and mounted atop the towers in yet another delicate operation that required several months of practice before the final installation. The two pinnacles are clad in brushed stainless steel.

Each tower used 11,000 tons of reinforcement steel, 2,825,120 cubic feet of high-strength concrete, almost 7,500 tons of structural steel beams and 830,000 square feet of glass windows.