The Leaning Tower of Pisa

1
The Leaning Tower of Pisa

• What went wrong?!

2
So What Will We Talk About?

• A brief history of the tower.
• Why the structure failed.
• The reason it still stands.
• The attempts to straighten the tower.
• The reason it still leans.

3
The History

• In Italian, it is called the Torre Pendente di
  Pisa
• It is the bell tower of the towns cathedral.
• Today it is 186 ft tall, with a 13 degree tilt.

4
History (contd) the construction

• Construction began in 1173 and continued off and
  on until 1372.
• Political crises caused breaks.
• Used multiple architects.
• First began tilt in 1178 with 3rd floor.

5
So What happened

• Engineering was often trial and error due to lack
  of technology.
• The foundation was poorly constructed and was
  only about 3 meters thick.
• Built on an ancient riverbed just 6ft above sea
  level, made up of weak sand and clay.

6

• The first lean of the tower was South.
• After trying to even the floors, it leaned North.

7

• This is an over exaggerated picture of the plan
  to make it straight

8
Why hasnt it fallen down?

• The soil compacted and settled due to the length
  of construction
• Without the break the tower would have fallen.
• It was built of limestone, which can handle more
  stress than most stone.

9
Attempts to Straighten the Tower

• Mussolini drilled and filed holes in the base
  with concrete, this made it tilt worse. (1934)
• Became unstable forcing the Italy government
  hired several engineers to stabilize it. (1964)

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Problems

• Was forced to close in 1990 due to increasing
  tilt.
• Later, it was stabilized by removing 40 cubic
  meters of soild from the raised end.
• Reopened to the public in
• 2001.

11
Why is it still leaning?

• Engineers decided not to straighten the tower for
  tourists.
• Instead, they gave it the relatively stable tilt
  of 13 degrees.
• It is believed to stand for at least another 300
  years.

12
So, We talked about

• The history and construction.
• The poor foundation which lead to the lean.
• That the solid compacted over time letting it
  stand.
• It still leans for a reason

13
The End

• Thank you