Wind and Earthquake Resistant Buildings 1

[ISCK]

"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!

 

[JStephen]

60 mph = 88 ft/sec if that helps. Sounds like a units problem.

 

[ISCK]

Thanks so much! Can't believe I overlooked that!