The Collapse of the
Tacoma Narrows Bridge
(1940)
Content
● Main Facts
● Map / Geographic Location
● Construction / Design
● Collapse – What does Physics say about it?
● Conclusion – consequences and meaning for today
Main Facts
●
Located in the U.S. state of Washington
●
Third longest suspension bridge
●
Spanned the Tacoma Narrows strait
●
Opened: July 1, 1940
●
Collapsed: November 7, 1940
Map / Geographic Location
English term
German term
Names
bay
Meeresbucht
Puget Sound
peninsula
Halbinsel
channel
Kanal
Kitsap
Peninsula
Tacoma
Narrows
• Journey: slow, long and expensive
• Only routes: by highway or by ferry
• Ferry system: “old-fashioned” and
expensive
Map / Geographic Location
English term
German term
Names
bay
Meeresbucht
Puget Sound
peninsula
Halbinsel
channel
Kanal
Kitsap
Peninsula
Tacoma
Narrows
• Journey: slow, long and expensive
• Only routes: by highway or by ferry
• Ferry system: “old-fashioned” and
expensive
Map / Geographic Location
English term
German term
Names
bay
Meeresbucht
Puget Sound
peninsula
Halbinsel
channel
Kanal
Kitsap
Peninsula
Tacoma
Narrows
• Journey: slow, long and expensive
• Only routes: by highway or by ferry
• Ferry system: “old-fashioned” and
expensive
Map / Geographic Location
English term
German term
Names
bay
Meeresbucht
Puget Sound
peninsula
Halbinsel
channel
Kanal
Kitsap
Peninsula
Tacoma
Narrows
• Journey: slow, long and expensive
• Only routes: by highway or by ferry
• Ferry system: “old-fashioned” and
expensive
Construction / Design
Engineering Challenge
• Water depth and the tides
• Length of the crossing
• long and narrow bridge
Planning Process
• Initially designed by Clark Eldridge
• Costs exceeded state’s funding ability
• Leon Moisseiff was consulted
• Result: Slenderest designed bridge
Eldridge
Moisseiff
Eldridge’s
Design
Moisseiff’s
Design
Main span
(length)
790 m
855 m
Side span
(length)
395 m
335 m
Roadway (width) 12 m
12 m
Deck structure
Stiffening trussess
(steel)
7 m deep
Solid plate
girder (steel)
2,4 m deep
Tower (height)
West Tower – 141 m
East Tower – 145 m
130 m
Tower
(stiffening)
8 bracing struts
4 bracing
struts
⇒ Eldridge’s plan for the piers
⇒ Moisseiff’s design for the superstructure
Collapse
• Video
• Windy
conditions: excessive oscillations
→ tourist attraction: “roller-coaster”
• Nickname:
“Galloping Gertie”
• Engineering
• 7th
professor: Frederick Farquharson
November: wind force of 64 km/h
Timetable
•
9:30 a.m.
bridge was closed
• 10:00
a.m.
twisting motion
• 11:00
a.m.
center span cracked
→ collapse
• Last
driver: Editor of local newspaper Leonard Coatsworth
• Last
man standing: Professor Frederick B. Farquharson
Natural Frequency
• Designed
• Related
to withstand 200 km/h
to resonance (natural frequency)
• Example:
shattering a glass with voice
→ voice resonated with natural frequency of the glass
→ wind resonated with natural frequency of the bridge
Natural Frequency
• Designed
• Related
to withstand 200 km/h
to resonance (natural frequency)
• Example:
shattering a glass with voice
→ voice resonated with natural frequency of the glass
→ wind resonated with natural frequency of the bridge
Natural Frequency
• Designed
• Related
to withstand 200 km/h
to resonance (natural frequency)
• Example:
shattering a glass with voice
→ voice resonated with natural frequency of the glass
→ wind resonated with natural frequency of the bridge
Conclusion – consequences & meaning for today
• New
bridge in 1950
• Moisseiff's
• National
Register of Historic Places (1992)
• Presented
• Boosted
• ⇒ The
•
career ended
as an example
research
bridge represent tragedy and triumph
Sources
http://www.wsdot.wa.gov/TNBhistory/Machine/entry.htm
http://www.wsdot.wa.gov/TNBhistory/Connections/connections1.htm
https://www.thevintagenews.com/2016/04/23/new-technology-used-findmystery-behind-pyramids/
http://www.history.com/this-day-in-history/tacoma-bridge-collapses
http://www.asce.org/project/tacoma-narrows-bridges(1)/
https://www.youtube.com/watch?v=XggxeuFDaDU