demolition of buildings-av
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Demolition of Structures
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Contents
1. Demolition of buildings: IS 4130
1.1 Planning
1.2 Precautions before starting
the work
1.3 Protection of the public
1.4 Sequence of demolition operations1.5 Removal of materials
1.6 Demolition of walls
1.7 Demolition of floors
1.8 Recommendations for demolition
of particular elements
2.Government Clearances
3. Demolition Methods
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Why?
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Demolition of buildings: IS 4130
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1.2.PRECAUTIONS BEFORE STARTING THE WORK
Danger signs shall be conspicuously posted all around the structure and
all doors and openings into it shall be barricaded or manned. However
provision for at least two independent exits for workmen to be given
During nights, red lights are to be placed on all barricades
Possibilities of any danger to adjacent structure shall require the people
to be vacate for the safety
The power lines, gas and water supply shall be cut off
All the mains and meters of the building are to be removed or protected
from damage
1.3.PROTECTION OF THE PUBLIC
Sidewalks and roads adjacent to the work likely to be affected are to be
closed or protected
A side walk shed is to constructed along the entire length of the sidewalk
if the distance horizontal is 4.5m or less and building is 7.5m or high. The
roof of the shed should be able to sustain a load of 73N/mm sq.
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1.4.SEQUENCE OF DEMOLITION OPERATIONS
All glazed ,sash, glazed doors and windows etc shall be
removed
All loose plaster is stripped off to reduce dust production All floor openings and shafts shall be floored over and
enclosed with guard rails
Demolition shall always proceed systematically storey by
storey in a descending order
1.5.REMOVAL OF MATERIALS
Dismantled materials may be thrown to the ground only after
taking adequate precautions. The serviceable and unserviceable
materials are separated in heaps. It should be lowered to theground through:
Chutes-wooden or metal chutes for the removal-at the centre
of the building for efficient building
Holes in the Floor-without the use of chutes-size should not
exceed 25 per cent of floor area
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1.6 DEMOLITION OF WALLS
Overloading of floors shall be prevented by removing the
accumulating debris
Walls shall be removed part by part
Structural or load bearing members on any floor shall not be cut
or removed until all the storeys above that floor have been
demolished and removed
In framed structures, the steel frame is left in place during the
demolition of masonry work
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1.7 DEMOLITION OF FLOORS
In cutting holes in a floor which spans in one direction, a slit of width not exceeding
300mm shall be cut at the first stage for the entire length of the slab along the way it
spans.
The demolition shall be started only after the floor in question and the surrounding
floor area for a distance of 6m have been cleared of people and debris.
Firm Planks given for the workmen to stand on to guard any unexpected floor collapse
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1.8 RECOMMENDATIONS FOR DEMOLITION OF
PARTICULAR ELEMENTS
Precast Reinforced Concrete - avoid toppling
Suspended floors-floors cut parallel to main
reinforcement
Reinforced Columns-reinforcement exposed at thebase
Reinforced Beams-Support ropes-concrete removed
from both ends by pneumatic drill
Cantilevers-supported or demolished first
Roof Trusses-If a pitched roof-the roof structure to
be removed to wall plate level by hands
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2. Government Clearances
1.1 PLANNING
A careful study of the structure which is to be
pulled down-the manner in which the variousparts of the building to be demolished are
supported and how far the demolition will
effect the adjacent buildings.
A definite plan for the demolition stage wise-
depending on the way the loads are supported
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Demolition Methods
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Oldest Method where a ball weighing up to 13,500
pounds is either dropped or swung into the element to
be demolished. Concrete may be demolished butsecondary cutting may be required.
3.1 BALL & CRANE METHOD
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3.2 DISMANTLING
Cutting elements and then removing with a crane is possible.The
cutting process may be sawing,water jetting or thermic lance.
Because the surface of cut concrete is almost smooth it is useful
when partial demolition required.
3.3 WATER JETS
Water jets reduce dust and eliminates vibration and fire hazardsUsed to cut straight lines and contours and access manholes.
1 inch penetration per minute is possible for RCC slabs.
3.4 THERMIC LANCE
Thermic Lance is created by packing a seamless mild steel tube with
low carbon rods and passing oxygen through the tube.Fusion creating
about 4000 to 7000degree Farenhiet can burn through 12 feet
thick.Rate of 2 to 3 inch per minute.
Vibration and dust reduced but smoke and fire hazards
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3.5 PNEUMATIC AND HYDRAULIC BREAKERS
Used for demolishing bridge decks,foundations and
pavements.
Hand operated and machine mounted types.
Underwater Demolition possible.
Remote controlled machines
Noisy,generate dust and vibrations
Sele ti e Dismantlin of RCC str t re
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Selective Dismantling of RCC structure
using Diamond Cutting Technology
Diamond Cutting technology is over five
decades old.What started as a simple device for the
marble industry in Italy has been perfected
to cut heavily reinforced concrete
structures.
The power of diamond cutting technologyis unlimited and unparalleled.
Diamond Cutting Machineries
Diamond Techniques
1) Flat Sawing
2) Wall Sawing
3) Core Drilling
4) Wire Sawing
http://www.cedima.de/engl/werkz/seil.htmhttp://www.cedima.de/engl/wand/301.htm -
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Circular and rectangular openings in RCC
Wall saw being set-up
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3.6 PRESSURE BURSTING
Mechanical and Chemical methods
Mechanical- in expensive, quiet and no
vibration
Chemicals used which cause expansion
internally
3.7 EXPLOSIVES-Implosion
Efficient means to remove large volumes of
deteriorated concrete
Dangerous and hence computer modeling
done to study the failure
Nitroglycerin, dynamite
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In most cases, blowing the support structures on the lower floors is sufficient for collapsing
the building, but loading columns on upper floors helps break the building material into
smaller pieces as it falls. This makes for easier clean-up following the blast.
Implosion of the Athlone Power Stationcooling towers on 22
August 2010.
The basic idea of explosive demolition is quite simple: If you remove the support structure of a
building at a certain point, the section of the building above that point will fall down on the part of
the building below that point. If this upper section is heavy enough, it will collide with the lower
part with sufficient force to cause significant damage.
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REFERENCES
IS CODE 4030 : Demolition of Buildings
Demolition of Concrete Structures by Hal Hudgins, Demolition Specialist
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