just a case study on wtc from the sources of information i got from internet.

1. Case Study
------- by Ponmathi.M

2. Case Study on "World Trade Center Tower
Collapse"

3. Overview
 Location - New York, USA
 Date - 11th September 2001
 Damage :
North Tower (WTC 1) - A Boeing 767-200ER series aircraft
hit between the 94th and 98th floors roughly at the centre
of the north face at 08:46.
South Tower (WTC 2) - A Boeing 767-200ER series aircraft
hit between the 78th and 84th floors toward the east side
of the south face at 09:03.

4.  Construction type - Steel perimeter frame-tube system
comprising external perimeter columns, central core
columns and concrete slabs on steel bar trusses.
 Fire resistance - Passive fire protection. Automatic
sprinklers system.
 Building type - Commercial.
North Tower: 417 m (101 storeys)
South Tower: 415 m (101 storeys)
 WTC 1 collapsed at 10:29, 102 minutes after the
crash.
 WTC 2 collapsed at 09:59, 56 minutes after the
crash.

5. The Building
 The twin towers of the World Trade Center (WTC)
were among the first skyscrapers built using the
framed-tube concept to provide lateral resistance to
wind loads.
 The steel framed-tube system comprised four major
structural components -
External wall
Central service core
Composite floor system
Hat truss system

6. Plane Crash and Damage
 On 11 September 2001, two passenger planes were
hijacked by terrorists and crashed into the World
Trade Center Towers in New York.
 When the two aircrafts crashed into the towers,
fireballs erupted and jet fuel spread across the impact
floors and down internal shafts, igniting multiple
floor fires immediately.
 The resulting fires spread throughout the upper floors
above the impact floors of the two towers.
 The twin towers collapsed shortly afterwards.

7. Gallary!

11. Sources of Information
 BBC News Online / World / America / America's day of
terror - UK Edition (2001)
 Federal Emergency Management Agency. (2002). World
Trade Center Building Performance Study: Data Collection,
Preliminary Observations, and Recommendations,
Washington, DC.
 National Institute of Standards and Technology. (2005).
Federal Building and Fire Safety Investigation of the World
Trade Center Disaster: Final Reports of the National
Construction Safety Team on the Collapses of the World
Trade Center Towers (Draft), U.S. Government Printing
Office, Washington.