Tacoma Narrows Bridge – Torsion Flutter

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Event details

Date 21.06.2016
Hour 16:00
Speaker Dr. Allan Larsen
Chief Specialist, Aero and Structural Dynamics
Bridge, Tunnel and Marine Structures
COWI A/S, Denmark
Location
GC B1 10
Category Conferences - Seminars
Abstract :

On 7 November 1940 the then newly built Tacoma Narrow Bridge collapsed in a 19 m/s gale creating some of the most spectacular footage in the history of civil engineering. While the monumental University of Washington investigation following the collapse stablished the wind to be responsible for the collapse a clear understanding of the aerodynamic mechanism was not established. As a result myths and speculations as to the reasons for the collapse emerged.
At the 60 year anniversary of the Tacoma incident the present author proposed a physical model for the large amplitude wind induced torsional motions (sometimes referred to as one-degree-of-flutter or instability) which lead to the bridge collapse. This model has generally been accepted as providing a satisfactory physical explanation for the collapse. Now at the 75 year anniversary the model is cast in a simple but rigorous mathematical framework which allows the amplitude dependent nature of the torsional wind response to be predicted.
This presentation will cover the collapse and observations to be made from the original footage and the following investigations, some of the myths created and the development of the authors travelling vortex model.


Biography :

Allan Larsen received his MSc in mechanical engineering from the Danish Technical University in 1979, the Von Karman Diploma Course in Fluid Dynamics in 1981 and a PhD in Flow Induced Vibration in 1984. Since 1989 Allan Larsen has been employed by COWI as a wind engineer for major bridge projects including the Storebælt Bridge - Denmark, Höga Kusten Bridge – Sweden, Chacao Bridge – Chile, Stonecutters Bridge – Hong Kong, Messina Bridge Project – Italy and Izmit Bridge – Turkey.

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  • General public
  • Free

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  • DISAL

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DISAL

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