huangyhg

debate over superdome as hurricane shelter
that place sounds like a coffin right now. pray for those who are about to receive. may god help them all.
well - i guess i just can't see the dome getting blown away. most major structures are designed for standard wind in the wind zone and no is very close to the coast so at least a 120 (the article says 130) mph wind would have been used. in addition - the shear size of the dome and the way its built would suggest that the overall stability of the dome isn't in question - as the primary wind would average smaller than the peak hot spots (component wind)that usually cause so much damage in homes and smaller structures.
in addition - being within an urban setting, the wind speeds are knocked down from the weather service speeds which are taken at specific "clear" zones at a set height above the ground - so the real wind hitting the dome wouldn't be the 165 mph speeds that you hear bandied about on the news.
here's a link to a wind speed map of katrina.
note that the category 5 is 135 knots which equals 155.5 mph. note also that this speed is at about 1800 km above ground.
good point but re
the speed can't be at any altitude, especially that high. i think this chart is a ground level speed as they compare this to a giant force three tornado that last for hours instead of seconds.
i know that in ivan i was measuring sustained wind speeds in excess of 120 mph for several minutes at 16 ft. the wind never dropped under 100 mph for over 1 hour, that’s all i could measure because my anemometer went away. i was told, never checked, that this the standard height for a wind gauge.
the superdome was designed and built when it wasn't surrounded by tall buildings. it was the highest thing around. there was some discussion during the construction of the dome as to the actual design speed. i know we had to upgrade the plant site form 100 mph to 135 mph. apparently 100 mph was the accepted standard for many years.
it's a nice looking structure (
most domes are designed with wind tunnel testing. at what design speed i'm not sure for the new orleans dome.
yes, but how you accurately perform a wind tunnel test on a structure back in the 1970's with new structures now adjacent to the superdome? the necking of wind between buildings can really increase pressures on adjacent structures. i just heard on the news that the occupants inside the structure can see some daylight thought the superdome’s roof.
it's also a bit tricky modelling for wind tunnel testing; in particular for 'funny' shapes. some of the coeficients aren't scaleable.
dik
what about impact loads from airborne debris?
how resistant is the structure to puncturing?
great discussion. funny how we engineers ponder these things. this morning i found myself wondering just how many older structures could sustain a category 4 or even a 5 hurricane.
i've never designed a dome, but having visited a few i would still think that the dome would be a safer place to go than most structures. if it's like any of the ones i've seen it has huge concrete beams and columns inside, which i would think would be great things to take shelter under/beside in the event of a hurricane. but i wouldn't want to be out in the middle of the dome with just the roof over my head. i would think that would be the weakest link.
i'm curious to see how much damage it does sustain.

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