Bao Guangjian is China’s most innovative steel specialist and the driving force behind Beijing’s impossible-to-build television centre – and even he is a little concerned about whether it’ll stay up … we went to meet him in Shenzhen
At the 2008 Olympics, China Central Television will be keen to enhance national prestige not only on the global stage, but also among a vast and sometimes volatile population. So it commissioned a brand new headquarters, and had the chutzpah to choose the weirdest building in the world, designed by Dutch architect Rem Koolhaas.
Last year Building talked to consulting engineer Arup (23 April) about the design. Now we’ve tracked down the specialist charged with erecting the 120,000-tonne steel exoskeleton. Bao Guangjian, “the China Steel King” is a fellow of the Chartered Institute of Building. He is embarking on the job of his life.
The CCTV Tower is not popular among the Chinese people I polled – partly, perhaps, because it was designed by a foreigner, but also because of its unnatural appearance.
“It looks like a monster,” says one Beijing engineer, wrinkling her nose.
But aesthetics aside, the big question is: how will its steel core and skin keep it up? It leans all over the place, and that angled horizontal section is itself 15 storeys high. “I am worried about that,” Bao admits.
When I talk to him, he is at the end of a long day showing CIOB president Geoff Wright around his hometown of Shenzhen. He’s already late for a meeting. In fact, the guy he’s meeting is drumming his fingers a few tables away in the bar. But within a few minutes of chat, Bao begins jumping to his feet to make his points.
He started as a welder in Shenzhen, the booming frontier town (see pages 45-46) in the early 1980s. In 1985 he pitched up outside a development and just started talking to people. He convinced them to let him project-manage the steelwork, and made his mark by raising the joints of steel columns by 300 mm – enough to stop welders from breaking their backs. That shaved many hours off the programme and was the beginning of his reputation as an innovator. This is a continuing story: he won a national award for scientific improvement a few weeks before our meeting.
The steel company on the CCTV tower is actually a joint venture between Bao and China’s biggest state-owned contractor, CSCEC. But Bao is the driving personality. “He can invite the nation’s specialists to solve the hard problems during construction,” says Lu Gang, CSCEC’s vice-general engineer and Bao’s right-hand man. He won against three other consortiums by locking 80 engineers up in Beijing for three months, making them address every aspect of erecting the steel. They had to understand Arup’s design, and work out how to fabricate the sections and weld them together. It’s a first for everybody.
CSCEC will source the steel from anywhere in the world – China effortlessly consumes one-third of the world’s steel these days. More worrying is the fabrication. The structure is so irregular that the number of unique sections and joints are too numerous to list. A few are pictured to the left. In the UK, steel erectors design and fabricate their own sections, and CAD-controlled rollers are standard. Not so in China. Bao has outsourced the fabrication – and even in this exercise, he is leaving nothing to chance. “We have negotiated with several factories in two different provinces,” he says.
They’ll be transported by sea or road and welded together on site. Work began last month, on 28 April, and is scheduled to finish in December 2007. At peak, 900 steelworkers will be on site.
Their plan of attack is to build the two towers at the same time and extend the cantilevered sections of the cross-piece simultaneously, meeting – fingers crossed – in the middle. This is the tricky bit, because the structure won’t be stable until the join is complete. They’re planning to bolt the two sections together in one-and-a-half hours. As they get close, engineers will measure the gap and order sections to fit. They’ll effect the join in late afternoon so the sun doesn’t warp the sections, and they’ll keep a massive jack to hand in case a little extra persuasion is needed.
Bao has a string of innovative, high-profile jobs behind him, but the CCTV tower is sure to secure his fame internationally. The link to CSCEC already has him in New York erecting a prominent council building and, again through CSCEC, he will be building a luxury hotel in Dubai. But, he is quick to add: “I am open to joint ventures with UK architects, project managers and consultants. They could take good advantage of our labour, management and technology.”
He might be the Steel King of China today but he has definite plans to be the Steel King of the World tomorrow.
Remind me, how was this thing designed?
“No building has ever been analysed like this one,” said Rory McGowan, Arup’s structural engineer, of the CCTV Tower in Beijing. He should know: he has just spent two years working out how to make it stand up.
The 231 m high, 54-storey building is a continuous loop made by two offset vertical sections, leaning 6°. These are joined at the top by a 15-storey horizontal link angling 90° in one direction, and at the bottom by a link angling 90° in the other.
And, as if that were not tricky enough, it’s in an earthquake zone.
McGowan’s challenge was to make the structure stiff enough to stand up, and flexible enough to absorb seismic tremors. Eventually a solution emerged. The structure would rely on an external square tube made of diagonal steel arranged as a mesh. Vertical columns help take the uneven load. The columns on the inside can support 200 storeys. Those on the outside would only be able to hold up 20 storeys on their own.
The leaning towers will sit on 100 m2 raft foundations at a depth of 7.5 m and will be supported by piles more than 50 m long.