Anchor Loads 1

[kos1]

Hi guys,

I need help with calculating anchor loads per anchor connection point. I have Calculated the total Seismic load and the wind load using NBCC (National Building code of Canada).
I can't figure out how to distribute this load over the anchor points. Attached is picture of the anchor plate layout. Any help would greatly appropriated.

 

[human909]

A quick question before we kick things off:

Are you a structural engineer?

 

[le99]

Both seismic and wind events can produce shear and uplift forces that should be distributed to the support element through engineering mechanics (P/A +/- My/I).

 

[dik]

Some questions:
[ul]
[li]Is that some type of equipment on a skid?[/li]
[li]Is the anchorage of the equipment to the skid or to the skid to the 'roof/???'?[/li]
[li]If a skid, then are there two line loads if it needs anchoring?[/li]
[li]What are the 3 pairs of anchoring plates for?[/li]
[/ul]

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[kos1]

@human909
I am a Design Engineer.

@le99
Yes, you are correct. I have those value already calculated. I need to find the individual load at each anchor points.

@dik

Yes, the equipment is on a skid. However, only those 6 plates that are attached at under the skid gets bolted to the concrete pad. I need to provide the loads per anchor bolts so the site engineer can spec the correct bolt needed to keep the tank in place.

 

[le99]

If you are in the US, you can get a copy of AISC Design Guide 1 (DG1). It is free for AISC members.

 

[human909]

I am a Design Engineer.

I'm not sure what that means. Have you undergone university level engineering training? This problem should be particularly hard, it can be worked out using highschool maths/physics if you already have the limit state seismic loads and wind loads.

For your uplift it is just working out the moment induced by you lateral loads and then resolving that by equal uplift and compression forces on your anchors. Given the symmetry this becomes rather trivial. Of course if your dead load is significant at all then you might not have any uplift because of the squat shape. So it becomes more a matter of shear which is probably pretty trivial too given there are 24 bolts.

 

[kos1]

I do have an Aerospace Engineering Degree. But my area of practice is pressure vessel and sheet metal design and fabrication. I have not solved these type problem and that is why im struggling. The part im struggling is understanding the overarching principle here, I can solve the math if i know what math I need to solve. If you can explain that to me, i would be greatly appreciate.

 

[human909]

It is static equilibrium problem. A quick google comes up with this as well as dozens of sources and videos. Like I said it is a highschool problem, plenty of information online.

https://www.physicsclassroom.com/class/vectors/Lesson-3/Equilibrium-and-Statics

The symmetry makes it even easier.

 

[HTURKAK]

The picture implies the equipment is rectangular tank / vessel on a skid . But it is not clear if the base slab is elevated or not . If the tank content is liquid and the base plate supported on the grid which is combined to skid, the total weight of the liquid content will resist to overturning ( for ground supported tanks, some portion contribute to resisting moment ) , more over, some portion of the liquid content mass will be effective for convective mode so, the total seismic force will be less than the rigid mass assumption.

The size of the tank ( squad size ) implies most probably tension force will not develop at the anchors.

I will suggest you to look the worked examples at sections 17 and 18 of the following doc.

https://www.fema.gov/sites/default/...rovisions-design-examples-p-1051_20160701.pdf

 

[kos1]

@HTURKAK, thanks for the link. Information on those section you mentioned, were very informative. Unfortunately they are for the US, do you know if something like this exist for Canada? I have reviewed both Building Code and the Fire code book, nothing similar exist.