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Re: Questions about Residential design and 1997 UBC

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Parkerres(--nospam--at) wrote:
> Thanks to Ralph and Dennis for their support of my realistic "design" approach
> to engineering.
> When one considers that our seismic load on the building is based on highly
> accurate coefficients such as Rw (Is it 6 for a steel frame? Is it 8?  Is it
> 12?  Why not 7.25?  Does the frame know if it's ordinary or special?) and Z
> and I ("We'd better chuck in an extra factor of safety of 50% - after all it
> is a hospital.), we shouldn't get too wrapped up in the precision of the
> analysis that the computer allows us to pursue.  Of course the same gross
> assumptions also apply to the loading for vertical design.  Why is assembly
> live loading 100 psf, why not 80, why not 92?
> All told, for design we always have VERY rough numbers going in.  We should be
> careful not to get too caught up in the analysis and modeling hype of the
> results. It's important not to lose sight of the big picture and the desire to
> design structurally safe and properly performing buildings.
> Bruce Resnick, SE
> Parker Resnick Str. Eng.

Donn Wooldridge RA/S
Phoenix, AZ