Structural Mechanics

1. Presented By
MD.IRFANUDDIN
( ANew Perspective)

2. -The St. Lawrence River became a
barrier to east-west
transportation.
-Montreal’s success was appealing
-So in 1887, the Quebec Bridge
Company was formed.
Purpose of The Quebec Bridge
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3. -The Phoenix Bridge Company of
Phoenixville, Pennsylvania was given
the contract
-The Head Engineer of the project
was Theodore Cooper
-One of the most respected bridge
builders at the time.
The Hired Help
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5. Dimensions of Bridge
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6. Concept of Bridge
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7. -Before construction was to begin
Cooper lengthened the span from
1600 ft to 1800 ft.
-Cooper also modified specifications
that would allow for higher unit
stresses.
-There was no preliminary tests or
A Change in Plan
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8. -Due to Cooper’s health issues
he only visited the site of the
bridge 3 times. This left a lack of
authority on the construction site
-The actual weight of steel put
into the bridge had far exceeded
the original weight
-Yet construction continued!!
Trouble During Construction
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9. The First Collapse: August
29, 1907

11. -Of the 86 men who were still on
the bridge at the time of the
collapse only 11 survived.
-Cooper’s career ended, and as a
result he retired from public life
and died in his home on August
24, 1919, at the age of eighty.
The Aftermath


12. -Financial troubles with the
Quebec Company
- Inaccurate theoretical estimates
of the bridge's weight
- Unchecked changes i.e.
Cooper’s high-regard
Reasons For Failure
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13. First Collapse (Cont.)
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Member Numbers of theBridge

14. First Collapse (Cont.)
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15.  On Sept. 20, 1917, the suspended span was
lifted into position and fastened to the
cantilever arms. At last, the world’s longest
cantilever bridge was completed and the first
train crossed it in October. Two months later
it was opened to regular trains, vehicle and
pedestrian traffic.
In 1919, the Princeof Walesofficially
opened the QuebecBridge to the public.
Final Completion
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16. -Anunderestimation of the self-weight of the structure
-Temporary splicing ofthe chords using bolts
-Theload carrying capacity had been overestimated
resulting in weakacross-sections.
-Thestabilizing bars(the crossing diagonals and
horizontals) were not strongenough to resist out-of-
plane buckling of the compressionchords
-Financial troubles with the Quebec Company
- Inaccurate theoretical estimates of the bridge's
weight
Major Causes of Failure
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17.  The collapse of the bridge finally led to the
development of Canadian designspecifications
for bridge structures.
 Engineering design is necessary for the
construction and methods of lifting operations.
 The responsibility of execution and design of
such an important structure must not be left in
the hands of one person.
Lessons Learned
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18. Any Query,
ask……
It’s now or

19. Thanks for your
Attention
Have a Nice Day

20.  Quebec Bridge Collapse
https://www.youtube.com/watch?v=xk1xEctDK0k
 Quebec Bridge SecondCollapse
https://www.youtube.com/watch?v=bCrZCzuf72A
Video References
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