Monday, March 17, 2014

Demolition -- Methods

Generally ~ the reverse order of construction to gradually reduce the height. Where space in not confined, overturning or explosives may be considered.

Piecemeal ~ use of hand held equipment such as pneumatic breakers, oxy-acetylene cutters, picks and hammers. Care should be taken when salvaging materials and other reusable components. Chutes should be used to direct debris to a suitable place of collection.

Pusher Arm ~ usually attached to a long reach articulated boom fitted to a tracked chassis. Hydraulic movement is controlled from a robust cab structure mounted above the tracks.

Wrecking Ball ~ largely confined to history, as even with safety features such as anti-spin devices, limited control over a heavy weight swinging and slewing from a crane jib will be considered unsafe in many situations.

Impact Hammer ~ otherwise known as a ``pecker''. Basically a large chisel operated by pneumatic power and fitted to the end of an articulated boom on a tracked chassis.

Nibbler ~ a hydraulically operated grip fitted as above that can be rotated to break brittle materials such as concrete.

Overturning ~ steel wire ropes of at least 38 mm diameter attached at high level and to an anchored winch or heavy vehicle. May be considered where controlled collapse is encouraged by initial removal of key elements of structure, typical of steel framed buildings. Alternative methods should be given preference.

Explosives ~ demolition is specialised work and the use of explosives in demolition is a further specialised practice limited to very few licensed operators. Charges are set to fire in a sequence that weakens the building to a controlled internal collapse.

Some additional references ~

BS 6187: Code of practice for demolition.
The Construction (Health, Safety and Welfare) Regulations.
The Management of Health and Safety at Work Regulations.

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