> Factors of safety for building structures are in the range of 1.4 for
> dead load (the structure and none moving load), and 1.7 for live loads,
> and a 0.9 factor applied to the material for defects, tolerances, etc.
> For lifting equipment like cables and chains, the factor of safety is in
> the 3 - 4 range. The structural engineer also needs to be concerned with
> the dynamic loading and resonant frequency of the structure. Some floor
> structures a few years back were light weight, long spans, and a walking
> person would cause noticeable deflections (vibration) of the floor.
> Today that issue is addressed by many building codes.

> If the reference below to the killing of numerous people is to the
> Kansas City Holiday Inn walkway collapse.

Actually Hyatt Regency but, yes, that's the one.

    http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

114 people killed! and about 200 injured.

Olin mentioned that - I was mainly using Bhopal as an example as it
seems to come closer to the sort of accident you might get. But the
walkway accident shows what can happen with an apparently minimal
change in implementation which isn't checked by the engineer for
earthquake resistance, or dancers or whatever.

..In NZ we had a somewhat similar but rather less fatal event at "Cave Creek=
".

     http://en.wikipedia.org/wiki/Cave_Creek_disaster

18 people fell - 14 died and 4 were badly injured.
A viewing platform was built extending over a significant drop. A
number of people in a hiking group were using  the platform at the
same time and it collapsed. Some few who fell 'rode the platform down'
and lived but most who fell died.

The platform was NOT loaded past its design limit - it was built
differently from its design. The plans showed that construction should
use bolts but it was built with 6" nails. Extremely adequate for many
purposes - but not when loaded with 18 people who are actively shaking
the platform at the time :-(.


Discussion of how disasters happen - based on cave creek but with
application to many similar including Kansas City, Bhopal, Comet,
 .... and the future nuclear power plant somewhere near you built
under far less restrictive free enterprise rules
(That's not JUST a dig - proponents of such systems MUST account for
the sort of thing this report and human nature highlight.

          http://www.massey.ac.nz/~trauma/issues/1997-3/isaac1.htm


  R
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