Techniques behind building demolition

1. TECHNIQUES BEHIND DEMOLITION OF
STRUCTURES
Shubhajit Dua
Civil Engineering
3rd Year
Roll-1358029
University Roll-12601313047

2. INDEX
I. Introduction
II. Objectives
III. Steps before Demolition
IV. Demolition sequence
V. Methods of Demolition

3. I. INTRODUCTION
 In general, demolition can be defined as wrecking or taking
out of any loadsupporting structural element of a building
(houses, commercial establishments, and office buildings) or
non-building facility (highways, streets, and other non-
inhabitable construction projects).
 It's a popular misconception that demolition is nothing more
than knocking down a structure and hauling the debris to a
landfill. That assumption is wrong on many counts, especially:
First, the process of planning for and completing a demolition
project is far more thorough and complex than simple
knockdown. Second, demolition contractors are master of
recovering valuable materials and minimizing need for
disposal. Almost of the structure is salvaged for reuse and
recycling then make the cost saved and bring more profit for
the owner

4. II.OBJECTIVES
 Old and damaged buildings ( due to earthquake &
other various reasons) which are prone to fall down
completely or partially must be demolished before
any fatal accident.
 When the important structural components like
beams and columns become absolutely insufficient
for service then there is no option other than
demolishing the building.
 When a new structure need to be constructed on
the site the old structure is demolished.
 For safety of neighbouring area a deteriorated
building is often demolished.

5. III. STEPS BEFORE DEMOLITION
1. Surveying
2. Removal of hazardous
materials
3. Preparation of plan
4. Safety measures

6. 1. Surveying:
The building survey should cover following:
 The construction materials.
 The existing use and, if possible, the past uses of the building prior
to demolition.
 Adjoining pedestrian and vehicular traffic conditions.
 The sensitivity of neighbourhood with respect to noise, dust, vibration
and traffic impact.
 Available site area to allow on-site sorting of building debris.

7. 2. Removal of hazardous
materials:
Asbestos Containing Material
 In the case when asbestos
containing material are
discovered, specialist contractor
shall be employed to remove such
asbestos containing material. The
asbestos waste should be
handled, stored and disposed of
as chemical waste in accordance
with the Waste Disposal
Regulation.
Soil Contamination Material
 In the case when possible soil
contamination material is present,
specialist shall be employed to
prepare soil contamination test
proposal and submit such
proposal to the Environmental
Protection Department for
comment.
Asbestos Material
Soil Contamination

8. 3. Preparation of plan:
 A plan showing location of the building to be demolished, sections
of the slopes with ground level contours and detailed topography,
ground removal and backfilling, distances of adjacent structures
from the building to be demolished.
 A layout plan of all floors of the building to be demolished, with
adequate sections.
 A plan showing the procedure for the demolition of the building.
 A plan showing the proposed shoring and temporary support to be
provided to the building to be demolished.
 In the case when powered mechanical plants and equipment are
used, a plan showing the route of movement of powered
mechanical plants and equipment.

9. 4. Safety measures:
Training and Communication:
 Demolition workers, including
plant or equipment operators,
shall go through proper job safety
training and be informed of the
potential hazards by attending
training sessions as well as on-
the-job training.
Equipment Maintenance:
 All equipment shall be tested and
examined before use. They shall
be properly stored and
maintained. The equipment shall
be inspected daily and results of
the inspection shall be recorded
accordingly.

10. Electrical Safety
 A properly connected power source from a local electric utility
supplier or a mobile electricity generator shall be utilized in
demolition sites.
Fire
 All flammable goods shall be removed from site unless they are
necessary for the works involved. Any remaining flammable goods
shall be stored in proper storage facilities. All furniture, timber,
doors, etc. shall be removed before any welding work is performed.
Fire fighting appliances shall be provided and maintained in working
conditions.

11. V. METHODS OF DEMOLITION:
A. Ball and crane
B. Dismantling
C. Pneumatic and hydraulic breaker
D. Explosives

12. A. Ball and crane
 .A crane uses a wrecking
ball, weighing up to 6120
kg, which is either dropped
onto or swung into the
element to be demolished.
Swinging the wrecking ballB. Dismantling
 Selective or complete
demolition of concrete
structures is possible by
cutting elements and then
removing them with a crane.
 The cutting process may be
by sawing, water jetting or
thermal lance.
Dismantling a beam

13. C. Pneumatic and hydraulic breaker
A common piece of equipment used for demolishing bridge decks,
foundations and pavements is a hydraulically or pneumatically
operated, boom-mounted breaker.
 A jackhammer is
a pneumatic or electro-
mechanical tool that combines
a hammer directly with a chisel.
Jack hammer

14. A hydraulic breaker is a powerful
percussion hammerfitted to an
excavator for demolishing concrete
structures or rocks. It is powered by an
auxiliary hydraulic system from the
excavator, which is fitted with a foot-
operated valve for this purpose.
Hydraulic breaker

15. E. Implosion
 In the controlled
demolition industry, building
implosion is the strategic placing
of explosive material and timing of its
detonation so that a structure
collapses on itself in a matter of
seconds, minimizing the physical
damage to its immediate
surroundings. RDX-based explosive
compounds expand at a very
high rate of
speed, up to 27,000 feet per
second (8,230 meters per
second)

16. Building Implosion

17. IMPLOSION OF OCEAN TOWER , TEXAS
 In December,2008 the developers cracks in the columns of parking garage.The
parking garage and the tower were mistakenly built connected, forcing the weight
down upon the garage instead of on more solid “expansion joints”. The use of
expandable clay, which compresses when weight is applied to it, compounded the
issue and allowed the parking garage to remain relatively unsettled compared to the
tower itself. Preliminary evaluation showed that the tower’s core had sunk 14 to 16
inches, while the attached parking lot had shifted less than half that distance.
 The 376-foot unfinished skyscraper was brought down with a controlled implosion on
December 13, 2009. At 55,000 tons, it is claimed that it was the largest implosion of
a reinforced concrete structure in the world.
Implosion of Ocean Tower , Texas

18. Process of Implosion

19. CONCLUSION
 It can be concluded that demolishing/imploding the
building structure will prove very useful, economical
and quickest for reconstruction.
 Leads to a safe and controlled demolition for the
occupants and neighbourhood.
 Development in techniques allows rapid demolition
with no harm to the environment.

20. REFERENCES
 http://www.implosionworld.com/history.html
 www.wikipedia.com
 http://archsd.gov.hk/media/11640/demolition_e2004
.pdf
 http://wiki.iricen.gov.in/doku/lib/exe/fetch.php?medi
a=m%E0%A4%BEr%E0%A5%8Dc_march_2013:a
chuta_rao.pdf
 http://www.concreteconstruction.net/Images/Demoli
tion%20of%20Concrete%20Structures_tcm45-
341335.pdf