C9.5 Demolition Flashcards
Demolition ball
suspended from jib raised and allowed to drop onto structure swung forward on line swung sideways risk of premature collapse
Piecemeal
using hand tools
preliminary method
controlled collapse / pre-weakening
removing key structural members
remaining collapses under own weight
disadvantages of pre-weakening
may collapse to greater extent than needed
may only get partial collapse
debris projection
dangerous pile of debris left
overturning
wire rope pulling
attached to main supports
pull using vehicle
issues with overturning
whiplash of wire if it breaks
forces may overturn vehicle
inadequate vehicle power to complete job
explosives - considerations
structural condition v size of charges divide structure into sections safety when drilling holes for explosives - premature collapse cast iron can shatter site security may create dangerous situation if fails
demolition hazards
falls of people fragile surfaces falls of material flying materials premature collapse overloading of floors explosions in tanks / confined spaces live electrics / gas projecting nails, glass etc asbestos silica dust toxic / flammable / radioactive from previous building use HAVs WBV
control measures
protective screens scaffold fans to prevent debris fall brick guards debris nets sheeting demarcation of danger zones audible warning - sirens visual signs safety helmets competent supervision protect machine cabs structural engineering assessments
pre-demolition surveys
site history structural condition location of services - underground / overhead responsibility for cutting off / sealing services structural design / supporting members identify basements / cellars ground conditions - suitability for scaffolding, p[lant & equipment site access means of waste disposal special requirements, eg sealing drains buffer zone around site shoring requirement
demolition SSW
in reverse order to how building erected
no freestanding wall unless deemed secure by competent person
use of scaffold platforms - tied to building
check scaffold security / ties regularly
keep entrances, passages, stairs clear
do not use stairs that have been disturbed
remove protruding nails
remove glass
adequate lighting
remove debris from floors to not exceed SWL
site security
perimeter fence
2.5 metres high
warning signage
viewing panels at different heights
noise controls
sociable hours of work
dust controls
close roads / paths
dampen down
review prevailing wind direction
use part demolished structure as screen
environment controls
mud / debris - road sweeping
exposed sewers - protect
interceptor pits to prevent water run-ff
