Determining 10 year recurring wind load for 100 mph & 50 mph using ASCE 7-10 and ASCE 7-16 1

[oengineer]

I am trying to understand/learn how to calculate the 10 year recurring wind load for 100 mph & 50 mph using ASCE 7-10 and ASCE 7-16. Suggestions/ comments are appreciated.

 

[Huevo]

[URL unfurl="true"]https://asce7hazardtool.online/[/url]

[URL unfurl="true"]https://hazards.atcouncil.org/[/url]

 

[oengineer]

@Huevo

This is not for a specific location on the map. I have been given these parameters and asked to calculate wind loads based on the 10 year recurring wind load .

 

[JAE]

There's some good discussion in the ASCE 7 commentary.

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[structSU10]

I think this question is oddly worded. You either need the recurrence interval for a specific wind speed, or the wind speed for a specific recurrence interval. These are both for specific locations, and can be mapped I suppose. There are conversion factors in the commentary of ASCE 7 to adjust recurrence intervals.

 

[oengineer]

I am basically trying to do this example :

Example: the 90 mph wind covering most of the country (which is a 50-year “design-level” wind) has a corresponding 10-year wind of 76 mph (=90 mph * 0.84 factor in Table C6-7).

The issue I am having is that this example is based on ASCE 7-05, and I am trying to determine how to do this for ASCE 7-10 & ASCE 7-16. ASCE 7-10 & ASCE 7-16 do not have table TABLE C6-7 CONVERSION FACTORS FOR OTHER MEAN RECURRENCE
INTERVALS.

 

[oengineer]

I am seeking information/clarification on how to determine these values for ASCE 7-10 & 7-16, since neither of these codes has TABLE C6-7 CONVERSION FACTORS FOR OTHER MEAN RECURRENCE.
INTERVALS

Could you please provide the location for the commentary section of ASCE 7-10 & 7-16.

 

[Huevo]

There are specific maps for 10 year MRI wind speeds in the commentary of both ASCE 7-10 & 7-16. There is discussion about how some of those are derived in the commentary. My recommendation would be to use the maps in the commentary or the websites above that list 10, 25, 50, and 100 year MRI wind speeds.

 

[ilyas415]

I haven't looked into this for a while, but I believe the ASCE7 conversion factors for the USA between different return periods all use the same basic equations.

If you look in the ASCE 7-16 commentary, equation C26.5-1 gives a simple equation for ALASKA which you can multiply by your 50-year return period wind speed to get wind speeds at other return periods (not valid for 1-year RP). The paragraph immediately below this equation also gives the reference for it... which is based on a paper by a famous wind engineer, Jon Peterka:

Peterka & Shahid 1998, Design Gust Wind Speeds in the United States.

I don't know if I'm allowed to give you a copy of the paper on here? Anyway, the equation is as follows:

[box]Equation (3) Non-hurricane areas: FRA = 0.36 + 0.10*LN(12T)[/box]

There is also an expression for hurricane areas in the same paper near the end (Equation (5)).

Both equations are factors to be applied to the 50-year RP wind speed.

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Ilyas

 

[oengineer]

@ilyas415

Thank you so much for this. Would you happen to know where this section for conversions is located in ASCE 7-10?

Using equation FRA = 0.36 + 0.10*LN(12T), it gives you pretty close to the same value shown in TABLE C6-7 CONVERSION FACTORS FOR OTHER MEAN RECURRENCE
INTERVALS for ASCE 7-05.

 

[ilyas415]

No problem.

I didn't realise until now, but the ASCE 7-10 commentary seems to be separate from the main document.

Found a copy of the ASCE 7-10 commentary here:

http://sfotoohi.ir/wp-content/uploads/2015/06/ASCE_7-10-commentary.pdf

I think the conversion table itself has been removed from the ASCE 7-10 commentary.

However, this commentary explicitly mentions the equation, rather than just making a mention to the paper. See Equation C26.5-2 (pg. 509). So the conversions are essentially the same.

Ilyas

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Ilyas

 

[oengineer]

@ilyas415

Thank you so much!