2. GOVERNMENT ENGINEERING
COLLEGE VALSAD
Prepared By :-
Guided By:- Prof. D. J. Patel
Team ID :- 65396
Sr. No. NAME Enrollment No.
1 Neha Jerambhai Bhanushali 130190106007
2 Harsh Chandravadan Rana 130190106048
3 Moxesh Hitesh Shah 130190106053
4 Shiraz Hanif Solanki 130190106055
3. ABSTRACT
Usually the life period of concrete structures is 40 to 90 years.
Existence of the structure is very dangerous to the occupants and
surrounding buildings after the design life period which may lead to
severe impacts and a cause of many deaths.
These structures often meet with disasters, city reconstruction and
higher residence demand due to increasing population which leads to
reconstruction or demolition of existing structures.
4. INTRODUCTION
Definition
“Demolition means destruction, tearing down, breakup,
removal of whole or a part of any structure with the help of
some equipments or other method in a controlled manner
with a legal procedure and consent of the local authority.”
Demolition is generally classified as
A. Commercial demolition
B. Military demolition
5. AIM AND OBJECTIVES
AIM:-
Suggesting an ideal demolition technique that can be adopted
in the given condition, considering the demolition factors
affecting it.
OBJECTIVES:-
To compare different demolition techniques.
To get the knowledge of their impacts on environment.
To study the preplanning for the control execution of demolition work.
To find major factors affecting the controlled demolition.
To have an overview on the demolition of special structures.
6. SCOPE OF WORK
Upcoming major projects like highways, railways, etc.
Demand for modernization and improve comfort.
Illegal construction.
Redevelopment of inner urban areas.
Post earthquake activities.
Building damaged in fire accidents.
Brownfield expansion instead of Greenfield.
8. LITERATURE REVIEW
PLAN OF WORK
PLANNING DESIGNNING EXECUTION
Site Knowledge
Health and safety risk
assessment
Prequalification and
selection of specialist
contractor
Utilities encountered
Structural survey
Stability report
including calculations
Demolition plan
Precautionary measures
Sequence of demolition
Site supervision and
inspection
Safety measures
9. 1) Conventional method
2) Mechanical method
3) Electric method
4) Microwave method
5) Sonic wave method
6) Advanced robotics method
7) Chemical method
8) Hydraulic jet method
9) Thermal lance method
10) Stitch drilling method
METHODS OF DEMOLITION
12. In general, the following sequence shall apply:
1) Utilities disconnection. Electricity, plumbing water lines, drainage
connections etc.
2) All cantilevered structures, canopies, verandahs and features attached to the
external walls shall first be demolished prior to demolition of main building
and its internal structures on each floor
3) When demolishing the roof structure, all lift machine rooms and water tanks
at high level shall be demolished in “top down” sequence to the main roof
level
13. 4) Demolition of the floor slabs shall begin at mid span and work
towards the supporting beams.
5) Floor beams shall be demolished in the order of cantilevered beams, secondary
beams and then main beams.
6) Non-load bearing walls shall be removed prior to demolition of load bearing
walls.
7) Columns and load bearing walls shall be demolished after removal of beams on
top.
14. Mechanical Methods
High reach arm
Adopted when the demolition work exceeds by 20m in height.
It consists of three parts-
1) Base tank
2) Long arm
3) Primary tool
attached to the arm
19. Wrecking Ball
Destruction is done by the impact energy.
Steel ball (weighing up to 6500 Kg) suspended from the crawler crane.
Can’t be used on Steel structure.
Less Control On Moving Ball.
20. Pusher Arm
Pusher arm attached, apply horizontal thrust to structure to be demolished.
Adopted for height is less than 15m .
2/3 height of structure < point of application of force < 600mm from top of structure.
21. Calm Shell
Calm shell progressively bites the structure from top to bottom either by deliberate
collapse or wire rope pulling.
The clam shell shall be operated not less than 1 m above the structure being
demolished.
22. 1) The sequence of demolition by machine is typically the same as
the top down manual method, except that most of the demolition
is done by mechanical plant.
2) The demolition begins with the lifting of the mechanical plant on
to the building top floor.
3) When rope or tie wire is used for pulling, the workers shall be
protected or stay away from the area within reach of the rope or tie
wire.
4) Adequate propping shall be installed at floor levels below the
working floor to safely support the operation of the mechanical
plant.
5) The movement of the mechanical plant shall only be within the
propped area. The propped areas shall be suitably marked.
6) The movement of the mechanical plant shall be prohibited within
2 m of the building edge, within 1 m of any floor openings or
any cantilevered structures.
23. 7) The mechanical plant shall be lifted onto the roof of the building by
the use of mobile crane or other appropriate means as approved.
8) The machine shall descend down to the next floor by means of a
ramp. The ramp may be a temporary structure or other appropriate
design.
9) The slope of the ramp shall be not steeper than 1.75 to 1 or as
recommended by the machine manufacturer.
10) As an alternative, the machine may also be lowered to the next floor
by the use of mobile crane
24.
25.
26. In the electrical method, electrical heating of concrete is done to
remove concrete cover by generating a continuous wide crack over
reinforcing bar.
Thermal expansion of bar occurs when low voltage direct current or
large current is applied and thus creating tensile stresses in concrete
cover.
Electric method
This method is based upon the principle of raising the temperature of concrete by
microwaves which results in breaking of concrete due to the generation of stress.
Main disadvantage – jamming of communication and harmful effects on human
beings.
Sonic Method
Demolition of large buildings which are to be turned down by application of high
intensity sonic energy.
Main principle that the structure is demolished at resonance frequency.
Microwave Method
27. Advanced techniques using
robotic machines
Identifying the project’s unique requirements and selecting the right machine to
ensure the work is done is a safe and efficient manner.
Robotic machines meet these unique challenges.
Smaller Robotic demolisher machines to get into those tight spots and if a project
has some tricky or confined spaces we have robotic equipment on hand to get the
job done.
28. Chemical methods
Explosive
The basic concept of blasting is removing the support element of the building at a
certain point and the section of the building above the point will fall down.
The explosives are just trigger for demolition and it is gravity that brings the
structure down.
29. Soundless Chemical Demolition
Method
Powdered chemical will swell or
expand continuously when placed in
water.
Main component used here is calcium
oxide which when mix with water
forms calcium hydroxides and causes
increase in volume
Main advantage of SCDAs is it does
not generate noise, vibration, toxic
fumes or flying debris
30. Higher pressure foam is inserted through an injection barrel into the bottom of drilled
hole in concrete. The foam posses high viscosity and stored energy which results in an
efficient and controlled destruction.
Control Form Injection
31. Hydraulic Jet Method
Water jets stream with flow rate of 95-150 litres/s is pumped at high pressure of
about 800 to 1300 kg/cm2 directed at the concrete surface to remove the cement
matrix and wash out the aggregate.
32. Thermal Lance
Thermal lance is used for cutting reinforced concrete in which temperature ranges
up to 2000-4000˚C.
Thermal lance is a tool that burns iron in the presence of pressurise oxygen to
create very high temperature for cutting.
33. Stitch Drilling
Diamond drills have been used to core holes in concrete up to 54 inches in
diameter.
Larger holes can be made by drilling a series of overlapping small holes in a
circle or straight line, called stitch drilling. It is generally used in the industries
where retrofitting is the major concern.
