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Post baseplates along varying grade

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bugbus

bugbus

Structural
Aug 14, 2018
498
I am working on a project where we need to install about 70 handrail posts along a walkway. The longitudinal grade varies from about 0% at one end, gradually steepening to about 7% at the other end.

The posts will sit on a precast wall, which will come with the anchor bolts cast in perpendicular to the top of the wall. However, it is a requirement that the posts are installed truly vertical. Hence, every post will have a slightly varying angle to the precast wall.

In the interest of keeping the steel fabrication as simple as possible, I would like to avoid every post needing a slightly different baseplate angle. Instead, I would like to divide these into a few separate types, e.g. one to suit the 0-2% grade, the next to suit the 2-4% grade, etc.

My question is, what sort of angle can be tolerated between the baseplate and the anchor bolts? In the worst case, there would be a 1% (or about 0.6 degree angle) difference between these. Would I need to think about tapered washers? Is there some other solution to this? Thanks in advance.

1_pvx3dz.png


2_fne28s.png
 
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I'd put the anchors in parallel to the post and not perp to the wall, with grout filling up the void. Holes the same way. You can increase the anchor a tad for embedment because of the slope; the increase in length will be minimal, but you can add an extra 1/4" if you like. [pipe]

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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Thanks Dik - do you mean instead of casting in the anchor bolts, to have a duct/void and grout them in vertically on site?
 
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I wasn't thinking about anchorrods... even them, I'd cast vertically; I was thinking post installed. You want the nut to be flat, and that happens when the anchorrods are perpendicular to the post baseplate.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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Your anchor rod template can have a bevelled base to account for the slope.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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Something like:

Clipboard01_p3sjid.jpg


So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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If the slope is uniform, you can have the baseplates parallel to the top of the wall and put the anchors in 'on a slope' but only if all the slopes are the same. You have to adjust the guard height for each post if the slope varies. If only slightly, then you might be able to use the same post length and adjust the thickness of the grout. The arch might have a bit of a problem with that. Epoxy post installed anchors are sounding better all the time, or maybe weld plates and headed studs. Just noticed it was precast. This would require sleeves and grout... but still generally vertical, not sloped.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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Thanks Dik

I suppose the only concern with this is that now every precast wall element will need to have its anchor bolts cast in at an ever-changing angle.

What I thought you were referring to previously is below:

3_bbcexl.png
 
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That's why post applied is better... putting 4 fasteners on a precast wall using corrugated sleeves will likely be tight. How thick is your wall? can you go to CIP plates with headed studs and weld the posts to this?

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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Something like...

Clipboard01_jabbak.jpg


So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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or maybe... with HILTI HAS E-55 Anchors...

Clipboard01_fxjrgn.jpg


So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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Is this what spherical washers are for? Never use them but thought this is their job.
 
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I'd go for the skewing the base plate on the post to keep the plate square to the wall and the post vertical. Of course you will need to look for anchor tightening clearance issues on the uphill side.
 
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Why not just keep the bolts with a 4"-5" projection and use a rounded structural hillside washer for each anchor bolt/nut? The Baseplate leveled with grout as you noted and the hillside providing the bearing you need
 
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Spherical washer might be a little pricey for this; I've usually used them for X-bracing. With precast, I'd likely go for the cast in insert. It is possible to add threaded studs to the top of the plate and bolt the base to it. For drilled epoxy anchors, I'd likely choose the last sketch.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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