What is the format of loads Provided By Vessel Vendors for Foundation Design? 1

[Ndrds19]

I will be in the process of designing mat foundations for vertical vessels, and working with the vendors, who are based out of the country, to receive relevant information like empty weights, operating loads and hydrotesting loads, etc. The vendor's engineers are also doing the wind and seismic analysis, besides a whole host of vessel calculations. My inquiry is only on the wind and seismic loads. This thread is not about checking the accuracy of the vendor's calculations, or the foundation design, but more about the format of the final foundation loads that will be sent to the foundation design engineer.

How do you tell whether the wind and seismic loads, given in terms of base shear and moments, are factored or unfactored? Is it in the procedures on how they derived the wind and seismic loads? Is it in the formulas, or factors, they use in the calculations?

What is the format of the foundation loads normally provided by the vendor? There was a similar question by another poster previously so I know I am not the only with this question. The responses he got did not answer my particular question, though. Hope someone can advise. Some elaboration would be appreciated.

Is it dependent on the vendors themselves, or do they all send it in a similar format, so that the engineer receiving them are better able to use them? I personally prefer to receive the unfactored loads so that I can combine them in load combinations myself.

A follow-up question. If the foundation loads provided were factored, did you modify it, e.g. dividing by a factor before using it?

 

[EZBuilding]

Ask the question to the vendor and verify there is an understanding of the methodology between you and the vendor's engineer.

Provide a sample calculation and ask them to verify it.

 

[Ndrds19]

Thank you so much, EZBuilding. That is a very good suggestion. I will certainly email and verify with the vendors. They are out of the country so any communication takes a least a few days. What have been your experience when receiving such foundation loads from the vendors? Do they tend to send it in a particular format?

 

[JoshPlumSE]

I assume we're talking about vertical vessels, right?

A lot of this is specified in the contract documents. If the vendor knows they need to comply with ASCE 7 loading, then that's what they provide. Usually unfactored.

Usually, the dead load is empty, operating and hydro test (like you said). This is usually just a weight, no overturning or shear unless there's something weird about the vessel.

They should give wind and seismic base reactions for both the empty and operating condition. Usually unfactored.

 

[JStephen]

For ASME vessels, loads will generally be allowable-stress based, unfactored. But confirm with the vendor.
A lot of this comes from vessel software, and may not be spelled out as clearly as you'd like; ask for clarification as needed.

 

[Ndrds19]

Thank you so much to everyone for all your responses, and would certainly welcome even more feedback. Want to shout out to JoshPlum, if I may. Glad to see you here. Just read that you'd left RISA. I've been using RISA a lot over the last few years and certainly have sent in my share of inquiries to RISA and have gotten replies from you numerous times, too. Good luck and all the best wherever you are.

 

[WARose]

Sounds like a RFI for the vendor.