Presenter: Mr Joseph MAK (HD) Preface Demolition
Transcript of Presenter: Mr Joseph MAK (HD) Preface Demolition
9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
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Preface• Thissectionistohighlightsomeofthoseareasthathavepotentialsafetyrisksinstructuralconstruction,
includingdemolition,foundationandbuildingworks.• Emphasiswillbeplacedonearlyplanning,designandspecificationprovisions.
DemolitionDemolition Plan• DemolitionplanispreparedearlybytheStructuralEngineerincorporatingallcriticalsafetyprovisions.• Theseplansaretobeincorporatedintotenderdocuments.• Whenthecontractisawarded,theContractorisrequiredtosubmittheirproposeddemolitionplanwhich
shouldbeinlinewiththeSE’sdemolitionplan
Demolition Planning Features
Double deck hoarding / covered walkway to protect pedestrians; locations and extent of hoarding should be clearly defined
Scaffold, nylon mesh and periphery catch platforms / fans to prevent demolished debris from falling out of the block
The route for movement of mechanical breaker must be defined in Demolition Plan. Adequate propping should be provided underneath
Stacking of demolished debris not to exceed allowable height. Debris is to be cleared from time to time
Barrier erected at the opening of refuse chute. Scaffold and nylon mesh at the building perimeter must be more than 1 meter height
Clamping instead of tack welding to bracing should be specified in Demolition Plan; tack welding is difficult to assess for adequacy
Presenter:MrJosephMAK(HD)
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Early identification of asbestos containing materials by asbestos consultant
Asbestos Handling• Asbestosremovalshouldbewellplanned.• Theseinclude: - Earlyidentificationofpossibleasbestoscontainingmaterialsbyasbestosconsultantbeforetender. - RequirementsforasbestosremovalspecialistcontractorstipulatedinSpecification.
Identification of Asbestos Containing Materials
Asbestos Removal Works
Asbestos removal works for fuse box
Asbestos removal works for grille panel
Chalk board covered by polythene sheet
Vacuum cleaner with HEPA filter
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
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Sealed drum
Respiratory protective equipment and protective clothing used for asbestos abatement work
Transferring sealed drum to the ground
Spray of water
Asbestos particles removing
Compartment for Asbestos Removal Works
Passage for Asbestos Removal Works
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Plan
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Designated asbestos sorting area
Transportation of sealed container to designated chemical dumping site
FoundationExcavation and Lateral Support (ELS) Works• Forlargescaleexcavationandlateralsupport(ELS)works,itisimportantthatStructuralEngineershould
designapretenderscheme.• TheschemewouldbeusedasabaseforcomparingwithContractor’sproposedschemeattenderreturn.• ThisallowstheSEtobetterassessthestructuraladequacyofContractor’sproposedscheme,aswellasthe
correctorderoftheELScost.
Engineer’s ELS Scheme at Pretender Stage
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Contractor’s ELS Scheme
ELS Works
Materials and Plant Handling• Safetyinmaterialandplanthandlingisoftencriticalinfoundationcontracts.• EarlyplanningbycontractorandcheckedbySEinmaterialsstorage,manoeuveringofplants, transportingofheavyandlargevolumeofmaterialsareessential.
Materials Storage
Proper storage of H-pile material
Store rack for RCD drill rod
Proper storage of steel casing
Proper storage of steel liner
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Plan
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Equipment Disposition and Transportation
CCTV in operator cabin
Warning bar & rear camera
Overload alarm of excavator
Lifting steel cage by 2 cranes (horizontal)
Lifting steel cage (vertical)
Overload alarm
Lifting casing (horizontal)
Lifting steel casing (vertical)
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Loading Test
BuildingLarge Steel Cage Erection in Pile Cap and Transfer Structures Large Steel Cage Erection in Raft Footing for Domestic Blocks
Large Steel Cage Erection in Raft Footing for Domestic Blocks(Shear Links not Required)
Large Steel Cage Erection in Raft Footing for Domestic Blocks(Shear Links Required)
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Final set up of mass steel kentledge
Less congested shear links
Typical RC Detailing – Minimization of shear links by new design approach
Typical concrete block kentledge
Congested shear links
Congestion of shear links can be mitigated by enlargement of member size
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Passage through Falsework
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Steel Fixing and Concreting at Heights
Adequate lighting and fencing off hazardous area
The upward projections of congested shear links pose safety concerns during fixing of the upper layers of the reinforcement bars
Bad example
Bad example
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
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Temporary working platform provided for concrete pouring at heights (below 2m)
Mobile working platform (above 2m)
Bad Examples
Working platforms suggested in COP
Working platform with adequate railings and toe boards was provided during working at heights
Good housekeeping in working area
Working platform provided for steel fixing works at heights (above 2m)
Working chair provided for steel fixing works at heights (below 2m)
Mobile working platforms for steel fixing or concrete pouring suggested in COP
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
By Use of Fabric Reinforcement at Walls
Mechanized and Precast Construction for Elevated StructuresBenefit of Rotary Symmetry
Large Panel Formwork
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Traditional rebar fixing
Ideally design block with rotary symmetry to avoid moving formwork to ground level
If rotary symmetry cannot be fully achieved, designated site crews should be assigned to look after every movement of formwork to ground level.
Fixing of fabric reinforcement
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Precast Facade
Precast Staircase
Semi-precast Slab
Precast Beam
Precast staircase is supported on concrete landing cast earlier so that temporary props are not required. Temporary props may be easily disturbed due to frequent passage of workers.
Avoid slab formwork construction and minimize nos. of proppings
Avoid insitu construction of tie beams at elevated positions
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Allow enclosed working floor for other construction
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Crane HandlingTower Crane, Material Hoist, CCTV and Double Chain Sling
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Tower crane CCTV, monitor and control panel
Lifting zones are identified during site planning stage maximum required lifting weight for the precast elements has been considered in the selection of crane system & jib length as well as in the location of tower cranes
Overlapping areas and sensitive areas were identified during site planning stage anti-collision system were installed to all cranes
Material hoist CCTV and recording
New design double chain sling for lifting of hopper
Walkie-talkie is provided for signaler
Traditional single chain sling
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9. Safety through Early System Planning and Structural Design Approach for Demolition, Foundation and Building Contracts
We care about people. We care about life. With concerted efforts, we strive to raise safety awareness and foster occupational safety.
Gondolas
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Previous arrangement –Two supports for one gondola holding down / fixing to roof floor
A close-up view of the hole for tying wire
Current proposed design –Two supports for one gondola tying to roof parapet
Conclusion• Safetyresponsibilitydoesnotrestwiththeworkersandsitesupervisorsalone.Itwouldbemoreeffectiveif
thesafetyDNAbeearlybuiltinthedesignandmanagementlevels.• Atdesignlevels,ifstructuralcomponentsincludingbothpermanentandtemporarydesignsarewell
consideredandadequatelyallowed,itwouldremovesignificantsafetyrisksforworkerscarryingouttheconstruction.
• Atmanagementlevels,ifconstructionmethodologyandplantandequipmentcontrolandhousekeepingarewellplannedandproperlymanaged,thehighsafetyriskstoworkersoperatingthesesystemscouldbemuchreduced.
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