through bolt in brick masonry 4

[bjb]

I have a very basic question. When you bolt through masonry (through bolt), I know that you use a threaded rod with nuts and plate washers at each end of the bolt. Do you also need to specify some adhesive in the hole, like Hilti HIT HY 20? The through bolt detail in the tech note from the BIA doesn't show any. I guess that if you did try to put something in the hole like grout or adhesive, you would foul up the threads of the rod. I have never used a through bolt before, but I want to use one now. Any guidelines on properly detailing a bolt through multi-wythe brick masonry are greatly appreciated.

 

[UcfSE]

I'll start by saying I haven't used through-bolts like you are suggesting either. Since there is provision for vertical loads with the bolt shear and bearing and tension loads with the nut and washer and bearing I don't see why you would need epoxy in it as well. If there is no nut and washer on both sides then definitely use the epoxy. Sometimes though the "belt and suspenders" solution isn't a bad idea depending on the situation. I would think that if you have several wythes, especially with an air space between, the epoxy might help you hold those together better, particularly when you have old masonry. I can imagine some one cranking down on a nut and pulling the wall closer together in an extreme case.

I'm sure others who have actually used this detail and know about its pro's and con's can be of better help.

 

[haynewp]

A couple of things that come to mind:

If it is a repetitive loaded anchor, I would think more about using chemicals. I wouldn't think brick to be a very good repetitive load base anyway.

I don't think you need an adhesive with a through bolt with a plate washer and nut. If you have enough load to pull the plate washer and nut through the wall, that little bit of adhesive isn't going to mean squat.

If you have other questions, Hilti and Simpson have very good technical service departments. If you call them, they will most likely tell you the least cost and/or strongest connection for your wall even if it does not include one of their products. That is been my experience with them anyway.

 

[apsix]

I have specified the use of grout in this situation, especially if supporting heavier loads such as floors on relatively old/weak brick. It is not for its adhesive properties so much, but to ensure even load transfer in a hole which is probably oversize and not all that smooth inside.

 

[bjb]

apsix, what kind of grout do you specify? A basic sand/cement/water mix, or non-shrink? Do you specify a screen tube so you don't just pour lots of grout into cavities in the wall?

I like the idea of putting adhesive in the hole to try to get a more even distribution of load. I think you could take a screen tube, cut one end off it, and put it through the hole. Then you could tape the cut end, and put your adhesive in. You could also tape the threaded rod so the threads don't get coated with adhesive as you insert it in the hole. You the then push the bolt through, puncturing the tape at the other end, and remove the tape from the bolt during the gel time of the adhesive. This is just my idea of a procedure, I am open to others suggestions or experience.

 

[37ed]

I always in this situation use a "sleeve" the lenght of the thickness of my wall.it keeps them from "cranking"the bolts too much and moving things that should not,but have not used chem systems here.

 

[AbelGus]

Another advantage of using an adhesive in addition to the bolts and plates is to keep water out of the system.

 

[bjb]

I spoke with an engineer from Hili, and this is what we came up with: Drill the hole, and insert a screen tube. Put tape over one of the tube, with a small slit. Completely fill the tube with HY 20 adhesive. Then push the threaded rod through, which will displace the adhesive into any voids, and poke the rod through the tape. While the adhesive is still in the gel time, attach the plate washer and nut to the end of the rod that is now covered in adhesive. The purpose of the adhesive is try to provide uniform bearing between the bolt and the brick masonry, and when it cures, you also have a column of adhesive that can resist crushing of the wall if they over tighten the nuts. I didn't think about the fact that it should keep water out, but that's an added benefit. I designed the through bolts according to a Tech Note from the BIA, which recommended that the equations for bent bar anchors in the Masonry spec could be used, I did not base the allowable values from the info. in the Hilti Tech guide.

 

[BoydZander]

What Tech Note from the BIA did you use for designing the through bolt? I'm not familiar with the acronymn BIA, can you please elaborate?

Thanks

Boyd

 

[UcfSE]

Boyd,

http://www.bia.org/html/frmset_thnt.htm

Check out the different links to the notes on the left, specifically 44 and possibly 44A.

 

[whyun]

BIA = Brick Industry Association.

Tech Notes can be found at their web site at

http://www.bia.org/html/frmset_thnt.htm

 

[bjb]

BIA stands for brick industry association. The tech note is "Technical Notes 44-Anchor bolts for brick masonry, April 1986". You should be able to get it at their website.

 

[henri2]

Would an evaluation report be helpful in a situation like this?