The Petronas Twin Towers and the sky bridge connecting them define a record-breaking gateway to the commercial heart of Kuala Lumpur, Malaysia.

The 452 m towers are 7 m taller than Chicago’s Sears Tower, and are equivalent to 95 stories each. Concrete strengths up to 80 Mpa (11,600 psi) are used in the central core and perimeter columns. Structural steel is used in the pinnacle, the sky bridge and the long-span floor beams that support concrete-filled metal deck.

The challenge for the design team was to devise an economical and buildable structural frame capable of resisting the vertical and lateral loads of the world's tallest building with an 8.64 aspect ratio. Design wind speed for the Kuala Lumpur area is based on 35.1 m/s (65 mph) peak 3-second gust at 10 m (33 ft.) above grade for a 50-year return period.

The structural properties, mass and damping of the building were studied extensively. They determined that the design virtually eliminated occupant perception of wind movements and accelerations. The 10-year return peak total acceleration on the upper floors is in the range of 20 milli-g, well within acceptable criteria.

Multiple two and three-dimensional static and dynamic computer analyses were performed for checks of accuracy and adequacy of the simulations. Static displacements and dynamic mode shapes were in very close agreement. The periods for the primary lateral modes are about 9 seconds, while the first torsional mode has a period of 6 seconds. A model of the superstructure of one tower was used to check member forces and lateral displacements and a second model of the two towers and the connecting bridge was used to check frequencies, and mode shapes. A third model was of the foundations only and was used to study settlements, pile forces and soil/rock stresses.

The total construction cost is approximately $400 million (RM 1 billion) is completed in 1997.

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