grain storage tanks on ground: lateral load design 2

[IJR]

I am a structural engineer, and I usually have to design ring foundations for storage silos on ground.

Seismic loads specified by silo shell designers usually cross-check well with my rough calculations, however the anchor bolt sizes seem to be too small to the point of assuming that they are there only for erection purposes.

Could someone provide info on how shell designers design the tank for seismic effects.

Also is there any modification made to Jansens or Reimberts equations if silo wall is corrugated?

Thanks. IJR

 

[ksuengrng]

While my primary experience is in tank/vessel design, I offer the following comments.

Shell design is based upon the standard required: API-650, API-620, UL-142, ASME Sec. VIII, and reference books published by independent authors. Good engineering knowledge/experience and knowledge of the path of force/moment travel is also important. Some of the more well known books are by Eugene Megyesy, Henry Bednar, and Milo Ketchum. Each of these books, codes and standards take into effect the seismic condition and how to design for it. One of the primary reasons why the anchor may appear insufficient is so that when a seismic activity happens on the large scale, you want the anchor to yield before the attatchment to the tank. In my experience, we never specified anchor bolts to be less than 1" in diameter. To get to that point of anchor yielding before attachtment to tank/vessel wall, anchor material may be changed, spacing may be changed, or number of anchors may be changed.

The shell design also takes into effect liquids and their sloshing modes along with the first instance of movement that indues forces on the walls, which inturn is to be transferred from the shell to the anchor to the concrete pad.

I hope this helps in some way.

 

[IJR]

Thanks ksuengrng

That bit has been quite a lot. If you dont mind, could you please give me some websites where I can download pdf documents or get info on the subject, as well as full title for the most available of the 3 books you have mentioned above.


Thanks once more and again. I design steelwork for industrial buildings and I am sure I will need your help every now and then.

 

[ksuengrng]

IJR,

The three books in question are:

Pressure Vessel Handbook by Eugene Megyesy available from Pressure Vessel Publishing in Tulsa, OK.

Pressure Vessel Design Handbook by Henry Bednar available from Van Nostrand Reinhold, Co in New York, NY

The Design of Wall, Bins, and Grain Elevators by Milo S. Ketchum available from McGraw-Hill. This book is older and may be tough to find.

You could get any of them from Amazon or Barnes and Noble. However, I bought some of them directly and through an excellent technical book shop called Brown Technical Book Shop (

http://www.brownbookshop.com).

Information available PDF wise I do not know. I do have a CD from AISC on their engineering journal that has provided excellent information on anchorage, among other steel and attachment items. You probably know of their web-site, but just in case, it is

http://www.aisc.org.

Would be more than happy to assist with your tank/vessel needs and/or questions.

Good Luck

 

[MJCronin]

Excellent...

The only other suggestion I would make is to purchase the flat bottomed tank code, API-650 which has extensive information on ring-wall foundations and is a good general reference for the type of work that you are doing...

An entire Appendix is in API-650 on the Seismic design of flat bottomed tanks and development of bolt loads.


The cost is about $130 and is available through API or the Brown Book Store in Houston, TX

Good Luck !!!!..................MJC

 

[IJR]

Thanks MJC

I have been using API650 and I have the code. My only worry was in that API is about fluids and my silo contains bulk material which may not slosh like fluids does

But I think you are right. At least for now API650 should be a good guide.