How a wobbly skyscraper in downtown Shenzhen has shaken public confidence in high-rise buildings
- One local media report said an unusual combination of factors had created an aerodynamic phenomenon known as the ‘Karman vortex street’
- The SEG Plaza in Shenzhen has been closed until an official investigation into the shaking has been completed
SEG Plaza, a 70 floor-plus skyscraper in downtown Shenzhen known as a mecca for electronic hardware merchants across the country, has been closed for thorough checks and possible repairs after a mysterious wobble in the past two days ignited public fears about the safety of the building.
A preliminary investigation indicated that a combination of three factors, including wind, the subway line below the SEG Plaza, and temperature differences inside and outside the building, likely all played a part in what some experts have said was the creation of an aerodynamic phenomenon known as the “Karman vortex street”, according to a report from the state-backed China Securities Journal.
On Thursday, an internal notice released by the building’s owner to the proprietors, tenants and merchants stated that as of Friday morning, no one would be allowed to enter the building until an investigation was completed, without specifying a time frame.
By Friday afternoon, however, merchants were busy pulling their merchandise out of the building while temperatures approached 35 degrees Celsius in the city. One tenant, apparently with nothing better to do, started to play a piano.
“Business has not been hurt too much so far, as we still do business online but who can bear this heat … We have to do the packing and delivering in the sun,” one merchant said.
Business has continued as normal for those working nearby and traffic has resumed. Vendors opposite to the SEG Plaza said there had been a jump in potential consumers “as the SEG is now a new hot destination to take selfies,” said one.
However, most of the curious onlookers did not stay around the building for long. “I will not hang around,” said one young woman taking pictures. “Tall buildings make me a little nervous now.”
The Karman vortex street, a repeating pattern of swirling vortices caused by the separation of fluid and wind around blunt structures, is considered to have been responsible for the sudden collapse in 1940 of the Tacoma Narrows Bridge, a suspension bridge spanning the Puget Sound in the northeastern US state of Washington.
In 1965, the Ferrybridge Power Station, a coal plant in England, went up in flames after three of its eight cylindrical cooling towers began to vibrate before collapsing.
A 2001 paper by then postgraduate student Jin Dianqi, now a senior engineer, drew public attention after finding that the working drawings for the SEG Plaza actually lagged behind the construction, according to a report by Chinese media outlet The Securities Times. The author said that the design of the building was modified while the building was under construction, and that an antenna on the roof had to be replaced because of a mistake during the design period.
China has 2,395 buildings measuring over 150 metres, the largest number of tall buildings in the world, followed by the US with 825 buildings, according to the Council on Tall Buildings and Urban Habitat (CTBUH), a Chicago-based organisation that specialises in the design and construction of tall buildings.
To date, China is home to half of the world’s top 10 skyscrapers, and 44 of the world’s 100 tallest buildings, including the 128-story Shanghai Tower, the second tallest in the world at 2,073 feet, CTBUH data shows. SEG Plaza is the 18th tallest building in Shenzhen and 212th in the world, according to CTBUH.
In 2020, when the Covid-19 pandemic hit the construction industry globally, China managed to complete 56 buildings 200 metres tall or higher, more than half the global total last year, according to CTBUH.
However, the Chinese government has attempted to put the brakes on the skyscraper frenzy. In April last year, Beijing asked local governments to slow down skyscraper construction because of environmental worries and concerns about how giant structures impact urban planning.
