Shrinking skyscrapers

Naomi Wilcock, Editorial Assistant at World Architecture News

A new method of demolishing buildings by ‘shrinking’ them from the top down has been pioneered in Tokyo, Japan. Using technology developed by Tokyo-based contractor Taisei Corporation, the method is currently being used to demolish The Akasaka Grand Prince Hotel in Japan in a contract that will last until May 2013.

The process involves a jack-down system, with the roof section of the building gradually lowered while being supported by jacks and an internal crane moving debris and other materials down to the ground floor. “It’s kind of like having a disassembly factory on top of the building and putting a big hat there, and then the building shrinks,” Hideki Ichihara, a construction technology developer for Taisei Corporation, told Japan Times.

Demolishing the 139m-high hotel, which closed in March 2011, floor by floor, the change has been almost imperceptible to many residents nearby. Dispensing with the previous demolition method of using cranes and explosive materials, this process, known as the ‘Taisei Ecological Reproduction’ technique (Tecorep) is reported to be a safer, cleaner and more ecologically sound way of demolishing high-rise buildings.

Video: Razing a skyscraper the ecological way

Other advantages include the reduction in dust and noise production, as using the Tecorep method can reduce dust levels by up to 90 per cent through taking the existing structure apart from the inside. As well as this, the top-down process means the building can be demolished in all weather conditions and the reduction in disturbances to nearby residents means that, with their permission, work can carry on twenty four hours a day.

The second time this Tecorep demolition method has been used, it offers an environmentally-friendly way to raze skyscrapers in densely-populated areas such as Toyko with Taisei Corporation looking to sell the technology abroad in the future. First conceived as an idea in 2008, the technology was deemed to be necessary owing to the limitations of the crane in demolishing buildings of over 100m tall.

With Japan having almost 800 buildings standing at over 100m high and the average lifespan of a building of this size being 30 to 40 years according to Ichihara, Taisei Corporation saw a need to develop a new kind of technology. Japan currently has 104 buildings which are more than 20 years old, so the need for technological development in the area of demolition is seen as paramount.

Ichihara commented: “We thought, is it really possible to safely disassemble buildings over 100m? We thought we needed to research that, which is how Tecorep’s development started.”

The ecological credentials of the technology can also be seen in the energy-producing cranes used to move the debris, as the movement of the cranes creates enough energy to power lights and other equipment. As well as this top-down method, other demolition processes are also being looked at, including the top-up method called the ‘Kajima Cut and Take Down Method’ by Kajima Corporation, which demolishes buildings from the ground floor upwards.

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