Just as man never thinks about his mortality, an architect or a civil engineer never thinks about the life span of the structure he designs or builds. It’s usually believed that his duty is limited to see the structure up and remain so in good condition during its life span. After the life of the building is over what needs to done or how it is to be done is not the concern of the architect or the civil engineer. Indeed, he is not paid for that nor does the client asks him to make a provision for the same at the time of construction. This has been the case whether the building is a skyscraper or single storeyed, whether it is located in busy street or a remote location. But also remember, demolition of a building (especially a tall one) is as painstaking and as time consuming as building the structure itself.
Skyscrapers that were demolished
|270 Park Avenue||USA||215||2020|
|One Meridian Plaza||USA||150||1999|
|Tun Razak Tower||Malaysia||150||2014|
Till date, the tallest tower to be peacefully demolished is 47-storey, 612ft (187m) Singer building in New York, which was taken down manually between 1967 and 1968. But the race to touch the sky has no limits – the world’s tallest skyscraper, the Burj Khalifa in Dubai, is at 2,722ft (829m) vastly taller than anything that has been levelled before.
How the buildings are demolished?
Demolition through implosion is the most common method used to disassemble a building but we have witnessed a very few such instances so far. Demolition becomes a trickier issue and may find protests if it has to take place in a crowded busy locality. Further, in the kind of densely-built areas where high buildings tend to proliferate such demolitions are not generally permitted and is also advisable.
Japanese construction firm Kajima has pioneered a more elaborate technique which involves knocking out the bottom floor and lowering the structures above it on computer-controlled hydraulic jacks. Stop-motion footage of the system makes it look as though a 20-storey building is sinking into the ground.
Using a high-reach mechanical excavator with a long arm to pull down the upper storeys is another method used in demolition. After the New Zealand earthquakes of 2010 and 2011, a 65m (213 ft) device of this kind nicknamed “Twinkle Toes” was imported from the UK to pull down damaged high-rises in Christchurch. Alternatively, if the exterior wall is a “curtain” – that is, it is not part of the structure, but forms an outer covering, typically made of glass – it can be pulled inside the structure using a crane, once the interior has been gutted.
The demolition technology is not stagnant but is evolving. Nowadays reverse building is the technology which is popular in which glass is removed first, then the frames, wall cladding taken off, then scraping away at the concrete and steel frames bit by bit. Concrete is removed to expose the steel reinforcing bars, which are then separately removed and recycled. In the course of this, unwanted material can be uncovered, such as asbestos, which needs particular care in handling. This methodical demolition helps to recycle most of the used material. Interiors are unbuilt the same way—in the reverse order of construction – remove floor coverings, cupboards, doors, and lightweight walls, strip the electrical wiring and pipes, take out air-conditioning and lifts, remove stairs and escalators.
Making the building unbuilding-friendly
The technology and the practice have moved still further. Now the architects design the structure creatively so as to enhance its utility after its expiry date. Techniques are being developed that assist in unbuilding and salvaging materials, even down to basic principles such as ease of access to pipes and wires, modular components, and simplified connection practices. It’s based on the simple logic that clarity of building structure and services make retrieval simpler. Less complexity of materials and components means a building can be untangled more efficiently. Some of the steps to make the structure unbuilding-friendly are:
- Simplifying the fastening devices
- Making them more mechanical by avoiding use of glues and sealants
- Avoiding use of toxic materials
- Selecting the materials with an afterlife in mind
- Giving more prominence to simplicity and accessibility in design
- Keeping clear set of as-built documents that map the original building to help while disassembling
At the end, the objective is to find utility in destruction. Sometimes what goes up has to come down. But pyramids have defied the law of gravity all these years. This is the source of inspiration for the planners, engineers and the architects. So, the trick lies in postponing the inevitable and making the life easier when it happens.