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Re: Wind Loading on Existing Structures

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I had occasion to do this for a building here in Houston. The only thing I was
able to do was to compare the current code (UBC) wind load provisions with that
in effect at the time the building was built, and use the friendlier one.

I, too, looked, but in vain, for such a stipulation, but was unable to find one.
Perhaps FEMA has such guidelines but I was unable to find them.

Unlike the seismic provisions, wind loading provisions consider wind loading to
be a "static" load, even though the maximum forces seen from an extreme wind
event are also of short duration relative to the life of the structure. Even
given the "mysterious 1/3 increase" of allowable stresses for ASD and the LRFD
load factors corresponding, the structural components don't venture out of the
elastic range when designing for wind, and therein lies your problem.

I think I'd take a different approach. Since the building has weathered a few
typhoons already, why not see if you can get wind speeds as local to the
building as possible from the Weather Service? Perhaps you can show that the
maximum sustained winds at your location are appropriate for analysis.

Also, maybe you can consider why the structure is so robust. Are there some
"non-simplifications" you can take into account in modeling?

For instance, I actually looked at the URM walls in my own structure, and also
the claddding as appropriate, and took those into account in assessing the
building. It made a huge difference compared to what I would have done had I
been doing the initial design.

> "T. Eric Gillham PE" wrote:
> Listserver Members:
> Does anyone on the list have any experience with Code required wind loading on
> existing structures?

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