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RE: Lateral Brace Deflection

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Ed

If you are assuming that the trusses are both buckling outward I would be
inclined not to consider wind loading also.  The reason is that wind loads
will help one chord while making the other worse but since both chords are
connected by the transverse beam the impact of the wind loads would seem to
cancel out.

Part of the rational for a lower wind load factor may be the realization
that in the very high wind loads it is unlikely that the bridge will be
fully loaded thus resulting in a lesser Kreqd.

Mark Gilligan


Message text written by INTERNET:seaint(--nospam--at)seaint.org
>Agreed, but I think the worst case (hair splitting here) is when the
trusses
buckle outward because it works with the dead load of the outrigger.  I am
also adding 0.3 wind, in accordance with AASHTO load combinations, I was
hesitant about the low factor, but it seems 100 mph design load in an 80
mph
area, with the consideration of 35 psf as if enclosed, when it is wide
open,
is conservative enough.
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