Drift Check with 10 year interval wind

[lutein]

I have read thru the post of 10-year interval wind for checking of drift in this forum. But, I still could not find the section in IBC or ASCE that allows us to use this to check wind drift on steel and concrete building.

Could someone please shed some lights into this matter of where I could find the exact code section?

thanks in advance!!

 

[csd72]

This is too specific an item to find in either of those, try the AISC design guide for crane buildings (cant remember the number).

 

[PMR06]

ASCE 7 talks about it in section C6.5.5.

They do not specifically say to use the 10 year value, but that is the one I see used most often.

Note that it is for non-hurricane areas only (V<100)

 

[lutein]

AISC Design Guide 3 does states that "For the evaluation of frame drift, ten-year recurrence interval winds are recommended due to the non-catastrohic nature of servicibility issues and because of the need to provide a standard consistent with day-to-day behavior and average perceptions."

I am trying to find the similar terms for concrete building.

 

[slickdeals]

The only place where there is a mention of a load case for serviceability is the wind load equation in the commentary of ASCE 7. Serviceability is suggested to be checked under D+0.5L+0.7W.

ASCE 7 also has a conversion table in the commentary to with factors to convert winds to different return periods. For a wind with a 10 year return period the factor is 0.74 (if I remember it right).

Hope that answers your questions.

 

[WillisV]

You will also notice that there is no section in ASCE7 or IBC that requires you to check wind drift at all...or perimeter beam deflection limits for facade loads...or floor vibrations. The building codes typically take a hands off approach to serviceability criteria as they can be fairly subjective.

 

[DonPhillips]

As it should, WillisV, since the codes are the minimum to maintain safe structures. Kinda like no requirement for air conditioning, just heating and ventilation. And no requirement for interior finishes, but if you install them, they must meet the minimum to prevent dangers to occupants.

Don Phillips

http://worthingtonengineering.com

 

[WillisV]

I totally agree - engineering judgement should still have its place somewhere...

 

[DonPhillips]

Agreed - and you have to meet your clients needs and serviceability should be directed by the client, who is paying the bills.

Don Phillips

http://worthingtonengineering.com

 

[Lion06]

There is a clause in IBC that allows you to use 0.7 of the 50-yr wind (which equates to the 10-year wind if your V<100 mph). I don't have it in front of me, but I'll look for it tomorrow.

 

[lutein]

StructuralEIT - If you do find such clause in IBC, please inform - I would really appreciate it.

In summary, although ASCE does provide conversion table, it does not explicitly direct the engineer to use 10-year wind for servicibilty (drfit)check.

Thank you all for your responses. I will keep researching on this, and will post my findings.

 

[WillisV]

1. The code does not require you to check overall building wind drift at all, though it is standard practice to do so.

2. Wind drift criteria are generally between H/400 and H/600 (see ASCE Commentary CC.1.1 and AISC Design Guide 3). Again these are recommended limits but not code required.

3. Drift limits are commonly taken under 10 year loadings. As aforementioned these can be calculated using ASCE7 - see a full discussion and example at: thread176-153232. Again this is not prescribed by the code - it is the choice of the designer.

4. IBC2006 Table 1604.3 Footnote "f" allows the use of 0.7W for member deflection checks.