Bolt For Shelf Angle

[Lake06]

I am designing a shelf angle to support masonry stones. The angle will be attached to an existing concrete retaining wall. The angle will need to support a tension load of 4,500LBS and a shear load of 1800LBS. What type of bolt is the best to use for this application? When I mean type of bolt I am referring to Mechanical Anchor or Adhesive Anchor. Open to suggestions/comments. I have been looking into the Simpson products.

 

[dcarr82775]

I prefer mechanical anchorage when I have constant tension on the anchor

 

[jayrod12]

dcarr, do you mean through bolts, or do you mean you'd prefer expansion anchors over adhesive?

What's the concern with adhesive? creep?

 

[mike20793]

I prefer expansion or screw anchors for constant tension applications, similar to dcarr. Even though ACI has an adhesive installation certification program now, I am still hesitant to use adhesives when there is constant tension. We had issues with installation in the past and it was enough to make me avoid using adhesive unless it's a last resort. I've used throughbolts when I was supporting brick off an LSL rim board for a multilevel wood building. For concrete and masonry, it's almost always a screw anchor or wedge anchor for me.

 

[Lake06]

Mike, what type and brand wedge anchor do you typically like to use or has a good performance history?

 

[mike20793]

Anything from Simpson, Hilti, Powers, etc. The major manufacturers all have products that are very, very similar to each other. For no particular reason other than their tables and software are easiest to use, we will often spec Simpson products. However, we allow for substitutions on our structural notes as long as the contractor submits load data stating they are equivalent to what we specified.

 

[Lake06]

Thank you Mike. I do like Simpsons software. Computing out long hand does take some time.

Relating to design, would you consider wind forces for this application or is this not required due to the presence of dove tails restraining the stones against the concrete retaining wall?

 

[Ron]

Agree with mike on brands. Have used all three. Considering that the shelf angle is for a retaining wall with significant exposure, you might want to consider stainless steel anchors.

Ditto on the used of epoxy with long term tension loading. Epoxy creep is likely.

 

[jayrod12]

Do any of you worry about water penetrating the expansion anchor hole and freezing?

That's been a concern I've had expressed to me often.

 

[thaidavid40]

Even though there are adhesives supposedly rated for long-term tension loads, I personally do not trust this application. My personal preference in these cases is to use a through-bolt with backup plate, or at least a mechanical anchor, which wouldn't be susceptible to creep effects.

Thaidavid

 

[Ron]

jayrod12....that can happen, but hole can be sealed with sealant or epoxy.

 

[Signious]

If you are concerned with proper installation (and not overly cost conscious) Hilti has a torque off head on the KwikBolt 3s. Once you twist enough to get the required anchorage the installation head shears off, exposing another head for disassembly if need be.

My typical detail for angle iron lintels / shelves specs 1/2" bolts at 16" o/c. All these bolt manufactures have in depth design data on their websites so you can check to see if they suit your numbers.

I second not using an epoxy/ready rod type set up. Messy, and the possibility for miss-installation is just too high.

Jayrod: Specify a rubber washer to be placed in front of and behind the steel washer. Problem solved-ish.

 

[Lake06]

Signious, couldn't the water get between the existing concrete and vertical leg of the shelf angle thus into the anchor bolt. Would it be beneficial to seal the top of the vertical angle between the angle and existing concrete with say a water proof membrane?

 

[Signious]

Yah, code in my area dictates covering the vertical edge 6" up with a membrane, building paper lapped behind the membrane and over the angle, 5mm drip edge off the horizontal leg.

Not sure if that is required everywhere though and rubber washers would work the same for the bolts & holes, not so much for the angle itself though.