Some held serious safety concerns about the skyscraper, but others hailed it as a revolutionary work of prefabricated urban landscape.
The more than 200-storey structure will tower 838 metres above the Hunan provincial capital and be made entirely of factory-made modules that will be assembled by workers in seven months.
Yin Zhi , a professor of architecture at Tsinghua University and a senior adviser to the central government on urban planning, said that while “prefab” houses were common, a prefab skyscraper was “insane”.
His biggest worry was safety. “What about wind? Or earthquakes? Or a fire?” he asked.
Broad Group, the developer, has been tight-lipped about the building, saying its structure was a trade secret, Yin said.
Broad released a 15-page presentation of the project on Saturday, saying that the building’s structure had been tested in three wind tunnels on the mainland.
The project also passed a seismic engineering review by a central government committee with hundreds of tests showing its all-steel structure could withstand up to magnitude 9.0 earthquakes, according to the presentation.
But Yin said even if the building could stand those forces of nature, it could still not guarantee the safety of its occupants.
The building will have 30,000 occupants, including more than 4,000 families.
“China’s best fire-fighting equipment and technology can do nothing for a fire above the 70th floor,” Yin said.
NBF – Nextbigfuture wonders if Yin was critical of the Shanghai Tower with 121 stories (to be completed in 2014) or the Jin Mao tower at 88 stories or the Shanghai World Financial Center at 101 stories
There are 14 buildings in the world that are 100 stories or taller and 13 more are under construction. 3 of those are already completed in China and 5 more are under construction (not including the 202 story Sky City).
The Burj Khalifa tower is supported by a large reinforced concrete mat, which is in turn supported by bored reinforced concrete piles. The design is based on extensive geotechnical and seismic investigations and analysis.
Costs now quoted between US$850 million and US$1.47 billion
Jiang Yong , another architecture professor at Tsinghua University who specialises in building structures, said Broad had been in the prefab industry for years and knew what it was doing.
“From a technological point of view it should be no problem,” he said.
Jiang’s major concern was cost. He said large prefab buildings faced resistance because steel was considerably more expensive than concrete and customers were unwilling to pay the high price.
Sky City cost about nine billion yuan (HK$11.3 billion), Broad said. However, the developer revealed little about how the project would be financed. Jiang said nevertheless that the project would reshape city landscapes if it was a success.
At a ceremony on Saturday, Zhang Yue, chairman of Broad Group, the developer behind the project, said the 208-story skyscraper would be completed by April 2014