Determing design wind speeds from raw data

[dsp88]

I'm looking for guidelines on how to determine design wind speeds for given return periods from raw climate station data.

I'm also interested in the importance of the frequency of data collection. I'm dealing with information that, at different locations, been collected at either 3 hourly, hourly or daily intervals.

If anyone can help me out or point me towards a good resource I'd be very grateful.

 

[RWF7437]

Not sure what you mean by "design wind speed". It would help to know what you are designing. If it is an airport then you probably want to plot a wind rose. There are sveral commercially availble programs that will do that for you. If you're trying to do a frequency analysis you should plot the data and do a regression analysis on it.

If you're designing a wind farm for power generation then direction may not be an important factor.

If you're designing a structure and need to calculate wind loads you can get some clues from building code requirements.

Always helps in this forum to tell people where your project is.

good luck

 

[IRstuff]

Unless you can get something like 50 years worth of data, it would be hard to determine what the design value should be.

As an alternative, you might look to MIL-STD-310 or some of the industry standards for wind design.

TTFN

 

[ishvaaag]

This is a task for codemakers. They need not only to average between lots of measures between many stations, but also determine the expected wind velocities (and changes of velocities) that assure you won't surpass a given probability of the proposed forces as determined by the code will be exceeded say with a 5% of chances in a big span of time; if timespan is to be allowed different, say for 1, 2, 5, 10, 25, 75 and 100 years.

Hence, taking a reductionist approach in which only wind velocities are counted on, you will need first to identify a distribution of the measured wind velocities that matches the best the data, and then use such distribution to ascertain which top velocity is not exceeded but in 5% of the measures. You may also do this just over the data, or their average for representative points for the zone or height etc. You have then determined a characteristic wind speed and then derive with the usual formulas the wind forces.

 

[ERV]

Try this thread for information:

thread507-78530

hope this helps.

 

[dsp88]

Thanks all,

This has been very helpful

 

[MPaul]

For short-term records of wind speed, check EPRI references on how to extrapolate to a 50 yr design speed. This method is often used for transmission tower design where recorded wind speed information is scant or has been recorded for only a short period of time. MPaul