SHANGHAI: The company building the 492-m-tall Shanghai World Financial Center, slated to be one of the world's three tallest buildings after its completion next spring, has installed two giant steel dampers to prevent swaying during heavy winds and reduce the impact of earthquakes.

Lu Xilin, a professor at Tongji University's Institute of Structural Engineering and Disaster Reduction, said the dampers' major function will be to prevent the building's occupants from feeling nauseated on windy days.

"The dampers also have the auxiliary function of reducing the amount of shaking that might occur during an earthquake," he said.

Lu's assistant, Li Peizhen, said this is the first time such dampers had been used in China.

Lu and Li have carried out several earthquake-prevention studies for the World Financial Center.

The Japan-based Mori Building Co Ltd is financing the construction of the 110-story building. The structure already stands 93 stories tall, or 416 m.

Information provided by Mori Building said two steel dampers, each weighing 540 tons, had been hung on the building's 90th floor to improve stability.

Li said the dampers are similar to equipment used in Taiwan's Taipei 101, currently the world's tallest building.

"However, the dampers take up less space than those in Taipei 101 because of new technology from Mitsubishi Group," Li said.

Representatives from Mori Building said sensors automatically shift the dampers to offset the force of the wind.

The system is activated whenever the wind blows at more than 20 m per second. The system will prevent the kind of swaying that leads to nausea.

Gu Ming, a professor teaching anti-wind design at Tongji University, said people staying at a five-star hotel that will occupy the 79th through the 93rd floors will benefit from the dampers, particularly during the typhoon season.

"According to national regulations, high-rise buildings should have anti-wind designs for when the wind blows at 40 m per second against the top floors," Gu said. "Without such conditions factored into the design, people on the top floors will feel sick from the swaying."

Mori Building described the system as cutting-edge.

Gu said people should not be concerned about strong draughts between high-rises, for example, between the Shanghai World Financial Center and the adjacent 88-story Jinmao Tower, in the Lujiazui zone.

He said a group of experts, including several from Tongji University, had tested conditions in the area in a wind tunnel.

(China Daily 06/08/2007 page5)