Structural Analysis IV
Outline of Structural Dynamics
Modern structures are increasingly slender and have reduced redundant strength due
to improved analysis and design methods. Such structures are increasingly responsive
to the manner in which loading is applied with respect to time and hence the dynamic
behaviour of such structures must be allowed for in design; as well as the usual static
considerations. In this context then, the word dynamic simply means “changes with
time”; be it force, deflection or any other form of load effect.
Examples of dynamics in structures are:
• Soldiers breaking step as they cross a bridge to prevent harmonic excitation;
• The Tacoma Narrows Bridge footage, failure caused by vortex shedding;
• The London Millennium Footbridge: lateral synchronise excitation.
Dr. C. Caprani