http://www.arup.com/eastasia/feature.cfm?pageid=8883The CCTV building has a nine-storey base, three-storey basement, two leaning towers that slope at 6° in each direction, and a nine- to 13-storey ‘Overhang’, which is suspended 36 storeys in the air. The building forms an asymmetrical arch, through which will be seen the adjacent Television Cultural Centre (TVCC). Together these two buildings will form the focal point of Beijing’s new Central Business District (CBD).
The leaning towers and the interconnecting section created a real challenge in engineering terms and required an innovative approach to make the uniquely-shaped building possible.
...A braced tube structure provided the solution giving the leaning towers sufficient stiffness during construction and allowing them to be built safely within tight tolerances before they are then connected and propped off each other. The braced tube structure also gives the building the required robustness to withstand possible seismic activity in the area and to provide an extra level of safety.
So the building was built to withstand earthquakes and had additional bracing to support it until the arch to the other building could be built. Plus, a reinforced concrete structure, not just structural steel.
Why, it's almost as if Arup had studied the WTC collapses and took those collapses into account when they designed future buildings!
Oh, wait, they did!
http://www.arup.com/_assets/_download/download582.pdfThe shocking events of 9/11 challenged both industry and consumer perceptions of how safe tall buildings are. Since then, building owners, occupiers and developers have increasingly called for building designs that are not only taller than ever before, but more robust as well. The following three case studies demonstrate Arup’s response to the new demands of this changing market.
...Arup’s response to the World Trade Center disaster was swift, establishing an Extreme Events Mitigation Task Force charged with evaluating the risks of disasters similar to those that have taken place in recent years, analysing the technical challenges they represent and developing design solutions to address them. With typical zeal, and chaired by the late Tony Fitzpatrick, then chairman of Arup’s Americas region, the task force mobilised the might of the firm’s in-house research and development capabilities and specialist teams on tall buildings, fire, materials, structural analysis and other disciplines to see what lessons could be learnt from the World Trade Centre disaster.
...Despite the catastrophic events and subsequent uncertainty surrounding the future of tall buildings in relation to safety, the industry has continued to grow to be as mighty as the buildings themselves. In fact, there are more tall buildings on drawing boards now than ever before, making this one battle in which technology has triumphed over terrorism.
So while some think the building's ability to withstand fire shows the WTC buildings could have withstood the fires as well, the truth is the WTC buildings' inability to withstand the fires informed the design of this and other buildings. The spectacular fires and the still-standing CCTV building are both witness to the building community's complete acceptance of the simple collapse of the WTC buildings.