huangyhg

wind and earthquake resistant buildings
"wind and earthquake resistant buildings" is a book that i am currently reading. it is authored by bungale s. taranath.
when i came across page 9 of the book, i found the following example:
f = v x s /d
the formula, is supposed "...to calculate the frequency of the transverse pulsating forces caused by vortex shedding...."
f = frequency of vortex shedding in hz
v = mean windspeed at the top of the building in mph
d = diameter of the building in feet
the following was proposed:
building height: building width = 6:1
natural frequency of vibration for building = 0.16 hz
assume a wind velocity of 60 mph
then "if the wind velocity increases from 0 to 60 mph (27.0 m/s), the frequency of the vortex excitation will rise from 0 to a maximum of 0.16 hz."
but how is this possible?
f = v x s / d = 60 x 0.2 / 110 = 0.11 hz, not 0.16 hz.
the equation tells a different story from what he's saying.
i tried to find the errata for this book, but i can't seem to find it. could somebody let me know if i'm right or point me to the errata website?
shouldn't it have said 88 mph for v, since 0.88 x 0.2 / 110 = 0.16 hz.
am i overlooking something subtle? in the book, he did say that "assuming a wind velocity of 60 mph...." for his example, but he never said that it was the mean windspeed at the top of the building.
thanks for your reply in advance!
find a job or post a job opening
60 mph = 88 ft/sec if that helps. sounds like a units problem.
thanks so much! can't believe i overlooked that!

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