diyapraveen.pptx

7/29/2019 diyapraveen.pptx

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Blast resistant structure

Presented by:

Praveen Kumar RCivil Engineering Department


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Blast Threats Types of threats

Terrorist threats

Petrochemical plants Accidents

War

Why are we concerned?

Events are rare, but consequences can be significant


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General Explosion Science Explosion

An explosion is a rapid release of stored energy characterized by a brightflash (thermal radiation) and audible blast.

Shock WaveThe rapid expansion of hot gases resulting from the detonation of anexplosive charge gives rise to a compression wave called a shock wave, whichpropagates through air.

Deflagration

Its an exothermic reaction (a moving flame front) which propagates from the

burning gases to the unreacted material by conduction, convection and radiation.

Detonation

Its an exothermic reaction characterized by the presence of a shock wave inthe material that establishes and maintains the reaction.


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Energy of Explosive

Thermal Energy

Kinetic Energy

Blast Energy


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Blast LoadsNeed to understand basic principles of blast loads and

their effects on structures for good design

To load the model correctly

Develop an accurate structural model

Correctly interpret analysis results


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Specific blast effects in defensive

structural design

Conventional structures are not normally designed to

resist blast loads

For example design snow loads range from about 5 psf to

about 50 psf.

The peak pressure in the blast pulse produced by 10 lb of

TNT at a range of approximately 348 psf!


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Blast Sequence


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Terminologies Stand- off distance

Refers to the direct unobstructed distance between a weapon and its

target

Height of burst

It refers to aerial attacks


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Blast load AT Blast

Nonlin

Blast load calculation R= minimum stand off distance

W= blast charge size

Scaled distance parameter=Z=R/0.33

By interpolating the scaled distance parameter with the

design curve, the equivalent design pressure impulses can

be calculated from the available charts.


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Test Methods

Open Arena-detonation of actual explosive device is required, should always beperformed by experienced blast engineering firm

Shock Tube-High pressure air pulses are released through a pipe or tube directed at thespecimen


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Blast Resistant Structural

Design

How different are seismic and blast effects on structures?

What is the role of structural ductility in blast resistance?


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Enhanced beam-tocolumn connection details for steelwork and reinforced concrete


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Blast resistant prefabricated units


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Conclusion The aim in blast resistant building design is to prevent the

overall collapse of the building and fatal damages

A building purely cannot be designed to be blast orballistic proof

The key is to limit the damage to an acceptable level

Good design is always a compromise between acceptable

damage and product cost


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Thank you

diyapraveen.pptx

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