petronas tower:

PETRONAS Twin Towers or alternatively known as Petronas Towers was the world’s tallest building from 1998 to 2004, until it was surpassed by Taipei 101. The tower itself is located at Kuala Lumpur, Malaysia with 88 habitable floors and 452 meters in height when measured from the main entrance to its pinnacle.
Nevertheless, the PETRONAS Twin Towers are the tallest twin towers in the world and is recognized as being the world’s tallest high rise of the 20th century.
The prominent features of the towers are the double-decked sky bridge, pinnacles and an advanced elevator system. Themain use of the building is for office space, although below the twin towers is Suria KLCC, a popular shopping mall and Dewan Filharmonik Petronas, the home of the Malaysian Philharmonic Orchestra.

The architectural design of the Petronas Twin Towers floor plan is based on simple Islamic geometric squares creating a shape of eight-pointed stars, reflecting unity within unity, harmony, stability and rationality.
To create more space, eight semi-circles were superimposed in the inner angles of the interlocked squares.
These semicircles are themselves anchored by the main structural columns of the buildings. The twin towers are symmetrically aligned and are connected with a suspended sky bridge.
The design details became prominent as the building rise in height towards the pinnacles. To maintain the vertical axis of the design, the towers are set back five times.

In the beginning, a race track was removed by the government as a move to ease the traffic congestion in that area. This opens up a 40ha piece of land worth hundreds of millions of ringgit, in the heart of KL free for redevelopment. With Petronas securing the financing of the development, Datuk Seri Dr Mahathir Mohammad, Prime Minister at that time wanted a building that would be identifiably Malaysian, that was of world class standards and which Malaysians could be proud of. Thus, an international design competition was held, with eight international firms invited. Finally, Cesar Pelli’s design, two slim 88-storey tower with a skybridge won the competition.
At first, there were no plans for the Petronas Towers to become the highest building in the world until Dr Mahathir suddenly thought of it; even during the building is already under construction. Mathematical recalculations were done and finally the plan to raise the height ofthe pinnacles is passed.

Construction started in 1993, with the piling of the world’s deepest foundations. The construction was done by two different contractors, sparking competition against each other. On the other hand, the towers were constructed with super high strength reinforced concrete due to the high cost of stete

At the top of the Petronas Twin Towers are structural steel pinnacles, which stood 73.5m tall. As two different contractors worked on the pinnacles, therefore one was made in Japan and the other South Korea.
Each pinnacle is composed of a spire, mast ball and ring ball. The ring ball consisted of 14 concentric tubes of differing diameters. In overall, the pinnacle is made up of 50 unique elements, lifted all piece by piece into place, making up a single 176 tonne in weight.
Functionally speaking, the pinnacle assembly are used to store aircraft warning lights and window washing equipment for the towers.

It was aIso the twin towers’ pinnacles that crowned the towers as the world’s tallest building in 1998 defined by the Council of Tall Buildings and Urban Habitat. This sparked controversy as the Sears Tower of USA is taller thanPetronas Twin Towers in the number of floors. However, under the rules used for rating the world’s tallest buildings, architectural spires count towards building height, while antennas atop a building do not.

The most prominent feature of the towers is the double-decked skybridge on the 41st and 42nd floors. The bridge is170m high and 58m long, providing access between the towers.

Center of skybridge as the observation deck with a circular window on top.

Interior of the skybridge on 42nd floor. The skybridge is open to all visitors.
Most high-rise buildings in the world use steel elements in their construction, but concrete was used instead of conventional steel in the construction of columns and core walls of the towers. Concrete was opted since it was a localmaterial that could be produced easily and Malaysia is quite sophisticated in concrete production which had ready labour in the industry. Besides, reinforced concrete also has twice the ability of steel to withstand vibrations.
To withstand 300,000 metric tonnes, a large concrete slab is used together with friction piles reinforced by grout (a mixture of sand and cement).

The polished facade is done with stainless steel extrusions and laminated glass covering or cladding the walls, reflecting Pelli’s vision of “multi-faceted diamond sparkling in the sun.” This minimizes heat gain by reflecting harmful UV light and unwanted solar radiation.

Each of the towers is supported by sixteen cylindrical columns that is made of concrete, encircling the core in the centre. They are placed on the inner corners of the star shaped plan with columns linked by slightly arched ring beams, also of concrete. The core and cylindrical frame system is constructed from in-situ high-strength concrete, including smaller perimeter columns around the two bustles. Some structural steel was used for typically long span floor beams to support concrete-filled metal deck slabs.

Horizontal steel bars or ‘teardrop’ and ‘bullnose’ steel sections are built into the polished facade which frames and linesthe open glass area. These sun screen brackets provide shade for the building and provide the appearance of flowing silver ribbon.
“For the Petronas Twin Towers, I tried to express the essences of the country. The building is rooted in tradition, but it is mostly about Malaysia’s aspiration and ambition,” said architect Cesar Pelli.