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