detonation of buildings

8/4/2019 Detonation of Buildings

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P R E P A R E D B Y :

S A G A R S H A H

F A C U L T Y G U I D E :

S O N A L T H A K K A R

Detonation Of Buildings(Explosive Demolition Of Building)



Demolition

The demolition of old structures and then subsequentreplacement of them with newer buildings issomething that has been going on for ages now.

Three types of basic demolition The Conventional method:

The entire demolition process, if one were to simplify it, would just involve disconnecting all the services and

then just knocking over the walls. This wouldautomatically cause the roof to collapse, completingthe destruction of the structure



The only thing remaining to be brought down or broken up is the left over concrete. The waste would then be used to clear and sent to the nearestlandfill site.



Reuse

The latest approach to demolishing buildings is moreenvironments friendly. The whole aim of the process is

to reduce the amount of waste. The valuablematerials are preserved for reuse these days. This may sometimes involve time consuming brick by brick dismantling of a structure.



Implosion

Implosion using explosives is the preferred method when it comes to demolition of tall buildings. The

method ensures that tall buildings are bought down with as little damage as possible to the surroundingstructures. This takes only a few seconds.



Why we need explosive demolition??

When a building is surrounded by other buildings, itmay be necessary to "implode" the building, that is,make it collapse down into its footprint.Explosive Demolition is mostly used when structureis more than 50 m high



Real Implosion?

Strictly speaking, an implosion is an event wheresomething collapses inward, because the externalatmospheric pressure is greater than the internalpressure. For example, if you pump out the air out of a glass tube, it might implode.



Basic Idea!

The Bigger They Come, the Harder They Fall : If you remove the support structure of a building ata certain point, the section of the building above thatpoint 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 forceto cause significant damage. It's gravity that brings

the building down.

http://c/Users/Sagar/Desktop/question232.htm

http://c/Users/Sagar/Desktop/question232.htm



Approach of detonation

In order to demolish a building safely, blasters must be mapped. First step is to examine architectural blueprints of the building, if they can be located, todetermine how the building is put together.



Kinds of demolition

Tipping building to its own side

Imploding building to its footprints



TIPPING

The main challenge in bringing a building down iscontrolling which way it falls. Ideally, a blasting crew

will be able to tumble the building over on one side,into a parking lot or other open area. Tipping a

building over is something is like felling a tree.



IMPLODING TO FOOTPRINTS

Sometimes, though, a building issurrounded by structures that must

be preserved. In thiscase, the blastersproceed with a trueimplosion,demolishing the

building so that itcollapses straightdown into its own

footprint (the totalarea at the base of the building).



DETONATORS & DYNAMITES

Clear any debris out of the building

Taking out non-load-bearing walls

Loading the columns with explosives

Type of explosive used depends on the structure i.e;

Steel

Concrete



BLASTING CONCRETE

Traditional dynamite is used

When the chemical is ignited, it burns quickly,

producing a large volume of hot gas in a shortamount of time. This gas expands rapidly, applyingimmense outward pressure (up to 600 tons persquare inch) on whatever is around it.

http://www.howstuffworks.com/question397.htm

http://www.howstuffworks.com/question397.htm



DEMOLISHING STEEL COLUMNS

Specialized explosive materialcyclotrimethylenetrinitramine, called RDX is used

RDX-based explosive compounds expand at a very high rate of speed, up to 27,000 feet per second(8,230 meters per second).



IGNITION OF EXPLOSIVES

To ignite both RDX and dynamite, one must apply asevere shock. In building demolition, blastersaccomplish this with a blasting cap, a smallamount of explosive material (called the primercharge) connected to some sort of fuse



CONTROLLING DEBRIS

To further reduce flying debris, blasters may wrapchain-link fencing and geotextile fabric around eachcolumn.

Blasters may also wrap fabric around the outside of each floor that is rigged with explosives



BIG BANG

Once the structure has been pre-weakened and allthe explosives have been loaded, it's time to makethe final preparations. Blasters perform a last check of the explosives, and make sure the building and thearea surrounding it are completely clear.

They use blasting machines to ignite the blast.



Case study:Club Med,Bermuda



CASE STUDY: CLUB MED,BERMUDA

On August 25, 2008 at 10 am the huge buildingshown above was finally imploded, recorded ontelevision and by the Discovery Channel of the USA,to make way for a new Park Hyatt Hotel.

a total of 2,000 holes into the various columns thatsupport the structure. Theholes were later filled withdynamite, over 700 pounds in total, to ensure the

building's implosion. Explosions in the core of the building weakened the

centre,pulling the building inward



In all there were 12 ‘slices’ to bring the buildingdown nto itself rather than falling apart.

All neighbouring residents were evacuated and taken

care of by the government



Advantages Improvement of worker health and safety. Risk reduction Control of noise ,dust and vibration Recycling of demolition waste Reduction of cost and time Limited use of heavy machinery like hydraulic hammers,

concrete crushers, breakers ,pulverizes, diamond sawing ,tools mounted on long/high reaching arms.

Easy and accurate blasting of structures, height more than 50m Fast demolition of bridges. Short period of demolition process.



Applicable in case of narrow space and different cultaccess to demolition site.

Cost effective and time saving.

Table given below shows the result of evaluation of different demolition techniques . ranked 1 (best), to 4(poorest)

Method Time Cost Environ

ment

pollution

Safety

Crane and Ball 3 3 2 Dismantling building from

top

4 1 3 With help of concrete

Crusher 2 2 1

Blasting 1 1 4 1



CONCLUSION

Structural explosive demolition had finally come of age on all major fronts, having been proven as aconsistently dependable, economically viable, andabove all, safe alternative to conventional demolitionmethods. And one thing was certain; it would just bea matter of time before private blastingentrepreneurs could develop a way to capitalize onthis revolutionary method of removing “unwanted"structures.



REFERENCES

www.howstuffworks.com www.implosionworld.com

www.discoverychannel.com

www.masterbuilder.co.in www.bermuda-online.org

www.dhgraffin.com

E-Book

Role of blasting technique in demolition E.K.Lauritzen.

J.Schneider.

http://www.howstuffworks.com/

http://www.implosionworld.com/

http://www.discoverychannel.com/

http://www.masterbuilder.co.in/

http://www.bermuda-online.org/

http://www.dhgraffin.com/

http://www.dhgraffin.com/




http://www.masterbuilder.co.in/

http://www.discoverychannel.com/

http://www.implosionworld.com/

http://www.howstuffworks.com/

detonation of buildings

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