Trough bolt on concrete wall
Trough bolt on concrete wall
(OP)
In this kind of connection where the bolt goes trough the wall and bolted at the other side of the wall.Should I only check concrete edge failure and ignore the pry out failure.because when i try to model it to hilti. it is failing in pry out categor. Thank you in advance






RE: Trough bolt on concrete wall
IF I was to check it, I would do a base plate design/check and then try to apply appendix D ignoring the back plate.
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
I'd definitely limit how much of the anchor embedment I'd consider using for shear. Probably about 8*diameter (of the bolt) or the minimum edge distance. (Whichever is less.)
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
It is caused (in part) by being close to an edge.
RE: Trough bolt on concrete wall
I disagree with this and believe that you still need to contend with pryout. Pryout arises from the eccentricity between where the shear is delivered and where it is resisted. And you still have that here. If HILTI says you've got a pryout problem with the anchors modelled at full thickness, then I'd still be worried about it.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
For pryout, I think you can make the case the back side plate adds some resistance but I have no idea how to quantify it.
RE: Trough bolt on concrete wall
Good point. But I am now wondering if the "le" to use in the shear breakout equations in Appendix D shouldn't be something more conservative than 8d or 12d. Maybe closer to the value called out in Sect. D.6.2.2 (for "torque-controlled expansion anchors"): le= 2da?
My reasoning would be: if it is a post-installed anchor (with a oversized hole).....you'd think that would cut down on how much would be in bearing.
(Kootk, if you are reading this....what do you think?)
RE: Trough bolt on concrete wall
Some ideas:
1) Look at the usual app D frustum but consider the depth of it to be the full concrete depth. And remove the back side resistance as there's no concrete to concrete boundary there upon which to exert tension.
2) Seriously eccentric punching shear.
I like the punching shear as I can tie that back to codified stuff more cleanly.
I think the same and probably for the same reasons. In an oversized, ungrouted hole, you're not going to get that spiffy laterally loaded pile stress distribution that we simplify with 6d/8d. Instead, you're just going to lean up against the edge of the hole in a way that concentrates all of the force there. This is part of why I rarely do through bolt connections unless:
1) It's straight axial load and I deal with it as punching shear or;
2) I treat is as a pretensioned friction connection which has it's own issues.
For something like this, if it can't be done with anchor theory, I consider that to mean that it can't be done. Sure, the back side plate feels good mechanically. But we aren't able to quantify that rigorously and, conspicuously, there doesn't seem to be much testing on these kinds of connections. And if I learned one thing from appD, it's this: our instincts suck when it comes to concrete anchorage. Can't. Trust. Self.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
its failing because the hilti is considering the pry out due to individual bolt which i think it should by group because of the presence of the base plate at the back? does it make sense?
RE: Trough bolt on concrete wall
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
@jlnj yup compression and vertical force to be exact
RE: Trough bolt on concrete wall
I'll try.
1) What are your loads?
2) What direction do your loads act? Are they reversible?
3) Where abouts are any concrete edges located that might affect the design?
4) What size is the steel member?
5) How thick is the concrete wall?
6) In general, what is this thing?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
This is a fancy picture of a pry-out failure that I found.
RE: Trough bolt on concrete wall
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
1) What are your loads?850KN COMPRESSION 600KN VERTICAL LOAD
2) What direction do your loads act? Are they reversible?NO
3) Where abouts are any concrete edges located that might affect the design? ITS CONNECTED TO 400X400MM COLUMN (FC=50MPA)
4) What size is the steel member?UB203X203X60
5) How thick is the concrete wall? 400MM
6) In general, what is this thing? ITS A BRACING END PLATE SUPPORT
7) Is the concrete new or existing? YES EXISTING
thank you
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
Great old PCI article for anyone interested. Believe this is where XR250's image came from: Link (PDF). Authors seem to imply that headed studs over 4.5d in length aren't really subject to pryout, though then go on to note that test results for studs over 4.5d actually came out lower than pryout equations would predict. Not sure if that's because pryout stopped governing (they mention earlier in paper that anchor shear starts to govern at about 4.5d) or if the actual equations are low.
Also old threads on eng-tips regarding this and discussions of pryout not governing or not being applicable when anchors are over a certain depth.
Concrete Pryout Strength of anchors in Shear (thread507-356645: Concrete Pryout Strength of anchors in Shear: Concrete Pryout Strength of anchors in Shear)
Anchor Pryout Check Limitation (ACI 318 Appendix D) (thread507-330541: Anchor Pryout Check Limitation (ACI 318 Appendix D)?: Anchor Pryout Check Limitation (ACI 318 Appendix D)?)
RE: Trough bolt on concrete wall
Given that you've got vertical load and horizontal thrust in equal measure, you probably don't need a ton of anchors to get this done. You can mostly get by on shear friction. I've shown a concept below. Not for the faint of heart of course. At the other end of the cowboy/conservative spectrum, you could cast a 6", full height bearing ledge on to the side of the column.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall
@mrhershey thank you for the reference. when I model it to HILTI they consider it a individual due to the eccentricity of the profile. and I also found out that the higher the embedment I use the higher the ratio became maybe its because of Ac/Ac0. it contradicts the statement that the higher the embedment the lower the risk of the connection to fail on pry-out.
@Kootk there's a little bit misunderstanding about the loading. what I mean on 850kn compression is horizontal load towards the column and 600 kn downward. well the output will still be the same because the 850kn doesnt have big impact on the bolt. and the profile has eccentrity of 90mm to the side of the column. and the detail that you provided do you have any reference that i can use to make it on paper. well its kinda complex but if thats the only way i think we should go with that.
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
RE: Trough bolt on concrete wall
I don't have a reference. At it's heart though, it's really just shear friction.
Not welding the bolts onto the plates but rather, welding on side plates to form a complete steel box around the column. Then you'd have a double shear-ish scenario I'd think.
Before you invest too much time in the bolted connection, I'd recommend ensuring that the column itself works in shear for the applied load. My preliminary calculations indicate that you'll need a LOT of ties in your column. Unless the existing column was designed anticipating the future installation of this brace, I doubt that those ties exist.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Trough bolt on concrete wall