5. DEMOLITION METHODS
When plant is used to demolish vertical features such as columns or walls, the columns or walls should not be so high as to create a risk of debris falling onto the plant or operator.
Any member to be severed( with grapples, shears or pulverising attachments) should either be effectively supported or, if allowed to fall, will not endanger persons, plant or damage the remaining structure.
Exclusion zones should be established where necessary to protect the safety of people who are working on or in the vicinity of the demolition work. No person should be in any area near the mechanical demolition where there is a possibility of being struck by flying debris. Areas in which shears are operating should be kept clear of workers, because of the risk of smaller pieces of metal( e. g. bolts) flying off when sheared.
For further guidance on the safe use of plant refer to the Code of Practice: Managing the Risks of Plant in the Workplace.
5.3 Induced collapse
Induced collapse involves the systematic / sequential removal of key structural members and the application of a force to result in the controlled collapse of all or part of a building or structure. Expert advice should be sought from a competent person such as an appropriately experienced structural engineer, before this method is used.
Induced collapse methods should only be used on detached, isolated structures on reasonably level sites. There must be sufficient clear space into which the collapsing material will fall. The space should be large enough to contain the collapsed material and enable equipment and personnel to be removed to a safe distance prior to the collapse.
For further information on induced collapse methods refer to AS 2601: The demolition of structures.
LOAD REDUCTION Structures which are not carrying their design loads may be pre-weakened prior to deliberate collapse. This pre-weakening should be carefully planned so that despite the removal of framework members and / or the partial cutting of load-bearing members, the remaining structure has sufficient strength to withstand wind or impact loads until the actual collapse is initiated.
Dead load can be reduced systematically by removing surplus material, machinery, roofs, cladding, walls and parts of floors before demolishing the structural frame.
Sometimes heavy loads are left at height to induce the collapse of the structure after movement is initiated. If this system is adopted, it should be carefully analysed and documented by a competent person( for example, a structural engineer) to avoid premature collapse.
WIRE ROPE, SLINGS AND CHAIN PULLING If using wire rope, slings and chain pulling to demolish a structure, the pulling medium should be a securely anchored winch or plant designed for towing and heavy enough to apply the required tension without sliding or lifting from the surface on which it is located.
30 CODE OF PRACTICE | DEMOLITION WORK