Wind uplift on tank roofs

[JStephen]

Several revisions back, API added a wind-uplift load to API-650, and has revised that and the overturn criteria several times since.
I was noticing recently that ASCE 7-16 has some wind-uplift requirements for tanks and tank roofs that are different from API-650, and that were not in ASCE 7-05 or ASCE 7-10, and also has provisions for increases due to grouped tanks.
And, those requirements potentially could require tank anchorage (and possibly increased roof strength) in a lot of cases where API-650 or other codes do not currently require anchorage.
Have other users run into this?
See Section 29.4.2 in particular.
Would it be reasonable to use a portion of the contents to resist this uplift per the API-650 approach, even when not in the load combinations in ASCE 7?

 

[r13]

The linked discussion indicates that there were uplift requirement from API, which refer to the use of ASCE7-05, or the simplified API wind uplift equation. It will not answer your question on ASCE7-16 though (I haven't read it). Link

I think it is essential to check the stability of empty tank by applying lateral wind and uplift simultaneously, that overturning could occur during maintenance.

 

[IFRs]

API 650 5.2.1.k.i specifically uses zero for uplift from wind acting on the cone roof if the cone roof meets the requirements of 650 5.10.4. Unless you are required to use ASCE 7 and not API 650, I would use API 650. The large dataset of API 650 tanks illustrate that considering wind uplift is unnecessary and adding anchors for this load condition adds expense for no benefit.

 

[HTURKAK]

I looked again 650 5.10.4 could not see such an exemption. Will you please quote the 'specifically uses zero for uplift from wind acting on the cone roof ' from the standard ?




5.2.1 k. Wind (W):

[V/120]2) uplift (see item 2 below) on horizontal projected areas of conical or doubly curved surfaces, where V is the 3-sec gust wind speed. The 3-sec gust wind speed used shall be reported to the Purchaser.]

 

[IFRs]

Here is 5.2.1.k.1 in its entirety (650 13th Edition):
1) Design wind pressure (PWS and PWR) using design wind speed (V): The design wind pressure on shell (PWS)
shall be 0.89 kPa (V/190)2, [(18.6 lbf/ft2)(V/120)2] on vertical projected areas of cylindrical surfaces. The design
wind uplift pressure on roof (PWR) shall be 1.48 kPa (V/190)2, [(31 lbf/ft2)(V/120)2] (see item 2) on horizontal
projected areas of conical or doubly curved surfaces. For supported cone roofs meeting the requirements of
5.10.4, PWR shall be taken as zero.

 

[HTURKAK]

Thank you IFR...

I have (650 11th Edition).

,
I understand with this statement ,The uplift wind pressure shall be taken as zero for the roof supporting structure .

PWR is still valid for OT ,sliding and other relevant uplift checks of the tank and elements.

API 650 discourages the attaching of the roof plate to the roof support members and explicitly forbidden for frangible roofs and allow for For Appendix F tanks .