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RE: loader surcharge at top of retaining wall

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In this case the energy input is due to the force of gravity acting on the
applied mass over the full amplitude of the resulting vibration in the
system.

The loader case probably does not have a large enegy input of this type
since we are talking about primarily horizontal motion.

Stan Johnson, PE
PS  It's wonderful to see that the list server has survived (dispite the
Bhima Incident and the Siege of Monika a few years ago).


> Timoshenko's Mechanics of Materials has an example which shows that a =
> statically applied sudden load corresponds to a impact factor equal to =
> 2. Imagine you have a simply supported beam with a mass M held at =
> midspan, so it just touches the beam, without imparting any load. If you
=
> suddenly release the load (no dropping height or initial velocity), you =
> get a deflection in the beam that is double that of the deflection from =
> a statically (infinitely slowly) applied load. Thus an impact factor of =
> 2 without any incoming kinetic energy. The above assumes no energy =
> losses, elastic behaviour, etc., etc.

> Regards,
> Gunnar Hafsteinn Isleifsson