HomeMy WebLinkAboutGate Wind Loads_CERTIFIED HYJG CONCRETE PAD KRIVONEN (1)•
Kr OAL'A
structural consultants
April 9, 2020
Job#: 20149
Ideal Manufacturing
2011 Harnish Blvd
Billings, MT 59101
Attn: Dave Hoiness
RE: Tilt -Away -Gate Design Update
Dave,
Recently you requested that our office conduct an update to the Tilt -Away Gate Design Design you had
performed by "Solid Solutions " in 2005. You explained that you would like us to take a look at the wind
pressures used and make sure that they were compliant with current code requirements. You asked us to
look at both the 150 mph design pressure as well as the 100 mph design pressure.
The previous designs were based on the ASCE 7-2 which used Design Wind Speeds. The 150 mph wind
speed was the maximum wind speed possible in the United States at the time. Current structural code
requirements are based on the ASCE 7-14. The current code refers to Ultimate Wind Speed values
which are higher than the original Design Wind Speed values.
For example, the 150 mph Design Wind Speed is equivalent to 193 mph Ultimate Wind Speed. Because
193 MPH wind speed does not exist on anywhere in the United States, we downgraded the wind
pressure to 180 MPH (which is the current maximum). Calculating the design wind pressure using 180
mph Ultimate Wind Speed we get the exact same pressure that was used in the original design. This
being the case, the 150 mph design performed previously meets current code requirement for 180 mph
Ultimate Wind Speed design.
The 100 mph Design Wind Speed previously used is equivalent to a current Ultimate Wind Speed of 130
psf. Using this ultimate wind speed I calculate a design pressure of 20.4 psf. This design pressure is
lower than the 25.6 psf used in the original design. This being the case, the 100 mph design performed
previously meets current code requirements for 130 mph Ultimate Wind Speed Design.
Please let us know if you have any further questions or concerns.
Kri'/Ofican
structural consultants
Respectfully,
Matt Krivonen, P.E.
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