Design and construction of the Petronas Towers

In 1991, local authorities of Kuala Lumpur decided to create a business district for the city, chosen to be the image of a modern city, and showing that way the great growing that was registering the Malaysian economy at that time. The symbol of that complex would be a twin towers, distinguishing and unique for the city.

The land of the old country club of the city were selected for that purpose, and an international contest, only open to invitations, was called. 8 different studios participated, and the winner design was the one by Cesar Pelli.

Pelli proposed two 88 storey twin towers, each one of 427m in height, and joint together with a bridge situated at the half of the total height, in 44 floor. The plant of the building decreases while it goes up, and it is based in a traditional form in the Islamic culture, a 12 vertex star. The building of the towers started in 1994.

At first, the towers were not planned to be the highest ones all around the world, because at the beginning the maximum height for the pinnacle was 16m less than total height of Sears tower. Later, with the towers already under construction, the promoters asked Pelli to increase the height everywhere it was possible. The architecture team started to work for pulling the towers trying to surpass the Sears tower in total structural height. With that purpose it was necessary to recalculate many structural facts, as well introducing the new models in the wind tunnel.

The solution chosen was not to increment the number of floors but to add a small dome and an integrated pinnacle to the towers’ structure, reaching that way the final height: 452 meters. With that solution, the purpose of surpassing Sears tower was a success, but not everyway, because Sears Tower would keep the tallest last floor record. This issue has been generating polemics since the finish of the Petronas, in 1998, until Taipei 101 was finished registering a new height record, surpassing even the Petronas and the Chicago one.

One of the main problems that appeared during the building process was the irregularities of the stony soil where it were planned to be built. That fact caused the moving of the original situation, to one 60m away, which the structural engineers thought was better for the towers.

The buildings lay over a concrete slab, which is situated over an underground “forest” of columns made of concrete and steel. The structure is based in a concrete core and columns. The metal structure was rejected because of the low disposition of Malaysian builders to work with a steel structure, as well due to the need of reducing vibrations in the higher parts of the towers.

The construction of the towers was relatively fast, thank in part to the promoters decision to put in charge of the building of each tower to different companies, that developed great rivalry to finish earlier their towers, due to the benefits in image and marketing that could give them.

One of the most distinguishing and at the same time problematic for the construction elements was the bridge that joins the towers at floor 44. That bridge has two levels, that allows the transit among the different equipments (offices, meeting halls, canteens, etc.), as well another escape way in case of fire in one of the towers.

The structural design of the bridge had an added difficulty: to accommodate the differences in movements and lying between the towers. This difficulty was solved joining the bridge to each tower with three supports with the shape of an inverted V, which allows the bridge to be equidistant of the towers in any case.

Apart of the functionality, the bridge has the mission of creating a space between the towers, which symbolizes a gate to the sky’s infinity.