ANCHOR BOLT SPACING

[roca]

ANCHOR BOLT SPACING

I have just picked up a new vertical skirt supported vessel design and the anchor bolt / hold-down bolt spacing is as shown in sketch A in the attached pdf.

Sketch B is what I am normally used to seeing (e.g. equally spaced, off centres).

Has anyone seen or made a design like this before for a skirt supported vessel?

The vessel is subject to wind and blast loadings.

Obviously whoever designed this has located the anchor bolts to match the supporting steelwork under it.

Cheers

 

[racookpe1978]

If your hand-drawn sketch is to scale, then the total vessel height is about 2-2 to 2.5 meters high, and less than 1.2 meters in diameter. 4x sets of 2x bolts in each set, 8x bolts total.

Those probably could work, you have to check the individual pull-out resistance of the bolts from the concrete at each of the four "corners." The base will act more like a 4-legged tank rather than a skirt held uniformly all the way around. That is, the skirt will resist wind loads "down" like a skirt on the down wind side, but held only in four places like a legged tank against upforce loads on the upwind side. So pullout loads on the up wind side will be the limiting factor.

And, 2 anchor bolts close together will have overlapping stress cones that 2 anchor bolts further apart won't be troubled with. Not a problem necessarily, just something to use when you size your anchor bolts and anchor bolt depths.

 

[roca]

Thanks
The drawing is a "sketch"
Next time I will add the term NOT TO SCALE

 

[gr2vessels]

Hey, welcome back roca.
As already said above, it's nothing more than a vessel supported in 4 points/locations. One can opt to double the bolts, providing the supporting structure or foundation is not adversely affected. Haha, not to scale!
Cheers,
gr2vessels

 

[dhengr]

roca:
Actually, Racookpe1978 was looking at (and thinking) ‘if the proportions on your sketch are about right, then here’s what I think of the bolt arrangements,’ and he had some good comments for you. To scale or not, you would be surprised at how important correct proportions in your sketches are in getting you a good answer, particularly when you show your sketch to an experienced engineer. And, you should learn that, and keep it in mind, if you have to ask these kinds of simple questions. An analogy would be a 16" deep WF cantilever beam which is drawn to look like it only cantilevers 2' vs. the 12' really intended, the old beam sketch depth to length proportions. They are two very different problems. Your two bolt patterns are more than likely dictated by two different support structures, as you suggested. And, either will work, but each requires a slightly different design approach to the skirt, and resolving the load reactions to the bolts. Either will work or can be made to work.