World Trade Center v0.1

8/6/2019 World Trade Center v0.1

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World Trade Center

What went Wrong?Ritesh Mittal (43)

Sunpreet Singh (50)

Sushil K Aggrawal (51)

Ullas Dewan(53)

Vishal (62)

Yogesh 68)


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World Trade Center


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Agenda

Attack timeline

Loss of life

Reason for tower collapse

Clean-up operation

Improvement in building design


8/22

American 11: Hit WTC North United 175: Hit WTC Sorth

American 77: Hit Pentagon United 93: Target White House

Crashed


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American 11

United 175

American 77

United 93

Attacks were well coordinated

8:00 AM 9:00 AM 10:00 AM

Departure Hijacking Crash

8:15

8:20

8:40 Delayed by 40 min.

8:20 8:45

WTC N

WTC S

8:45 9:03

8:50 9:37

10:039:28

10:03

10:288:00

10:30 AM


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Deaths and damage

American 11 87

United 175 60

American 77 59United 93 40

WTC 2,606

Pentagon 125

Total 2,977

In addition, 350 firemen also

died

Buildings

Four high rises collapsed

Four partially collapsed

Twelve suffered major

structural damages

In addition, 350 firemen

also died


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What saved lives?

Measures taken after 1993 blast helped evacuate the

towers fast

Battery operated lights in exit stairways

Public address system to address tenants

Frequent fire-drills


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Clean-up efforts

Required 24 months

Removed a million tons of debris @ 10,000 tons/day

Used ~30,000 truckloads of debris

Employed excavators reaching 100 feet

Used cranes to hold as much as 1,000 tons

Excavated 300,000 tons of steel

Land-filled 70,000 tons of concrete and rubble


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Why the towers collapsed so fast?

Were the towers structurally deficient?

Did the steel columns melted?

Did the fire suppression equipment failed?


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Tower structure

Tube-frame structural

design

Acts like a 3 D

hollow tube

Cantilevers

perpendicular to theground

Resists lateral loads

generated by winds,

seismic activity

Columns and beams

constructed of steel Floors constructed of

concrete


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Towers collapsed within 2 hours

Quick ignition of jet fuel generates intense heat

Steel in the columns loses half its strength

Steel columns deform causing buckling and crippling of columns

Floors above the buckled columns fall

Floors below crushed due to the weight of the stories above them

Whole building collapses due to domino effect


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Failure of steel

Two reasons

Loss of strength due

to the temperature of

the fire

Loss of structuralintegrity due to

distortion of the steel

from the non-uniform

temperatures in the

fire


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Improvements in building design

Focus on securing the building

Or

Focus on better safety and evacuation

system


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Securing the building

Build redundant systems Many of the redundant systems may not be used during the life of a

building

Building may not be cost viable Huge construction cost

Huge maintenance cost

Practical difficulties


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Safety and Evacuating system

Build systems to evacuate a building in the shortest

possible time

Build systems to save tenants from toxic materials Fibrous glass, computer screens, asbestos, lead mercury, etc.

Limit the stories in the building

American Society of Civil engineers recommended this

High rises will be cost viable Less construction cost

Less maintenance cost


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Recommended changes in building codes

Upgrade emergency communication systems

Speed up notice of evacuation

Speed up safest path of egree

Upgrade emergency illumination system

Better fire protection from

Smoke inhalation

Energy absorbing materials

Toxic materials

Height of buildings to be limited to 60 floors


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Thank You

Date post:	07-Apr-2018
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World Trade Center v0.1

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