Long-Slotted hole size 1

[Lion06]

Are the hole dimensions in table J3.3 for long-slots the maximum allowed? What if you need to provide a longer slot to allow a beam to deflect without loading a wall?

 

[WillisV]

http://www.aisc.org/MSCTemplate.cfm...tomSource/Faq/SteelInterchange.cfm&FaqID=2572

Though it "is not an installation in accordance with AISC or RCSC specifications" as a personal opinion I would not have a problem specifying longer slots than standard where required.

 

[nutte]

The dimensions in Table J3.3 are the maximum. The text in J3.2 says, "The maximum sizes of holes for bolts are given in Table J3.3 ..." To exceed that is to violate the specification, if the bolts in question are intended to transfer load.

If you need more movement than a long slotted hole allows, you should look at a different connection type. A seat that will allow sliding, perhaps?

 

[Lion06]

This is for a shearwall that has a Beam over top of it and in the plane of the wall. I don't want the beam to put axial load in the wall, but it is a shearwall, so I need to transfer shear into it. To allow the beam to deflect without loading the wall, I need 1.4" (for deflection) and 0.5" for the diameter of the bolt.
It will be an angle welded to the bottom of the beam and anchored to the side of the wall.

 

[civilperson]

Try a stiffer beam for lesser deflection or put slots in both the beam and in the connector.

 

[Lion06]

How will slots in the beam help? The angle is welded to the underside of the beam. I am already using an HSS 12x12x5/8 and can't go any deeper for architectural considerations. I may end up making it a bearing wall.

 

[lkjh345]

Are you counting on the full shear capacity of the bolt being transfered into the wall?

If not, personally, I would have no problem using 2" long vertically slotted holes in an angle to transfer shear into another element (shear wall in this case) if I am only transfering a nominal amount of force through each bolt. If fact, coincidently, I just did 3 or 4 details doing that exact same thing this morning. I am only counting on about 2 kips of shear for each 3/4" diamter bolt. I'm not worried about it.

Doing something like this is not all that uncommon.

 

[Lion06]

I am counting on roughly 50% of the shear capacity per bolt. They are 1/2" diameter expoxy anchors into a bond beam at the top of a CMU wall.

 

[slickdeals]

Just out of curiousity, how is the axial load from the beam being transferred. A sketch could help. Is the beam supported on something beyond the wall?

 

[PanamaStrEng]

The way I see it, the fastener will most likely be loaded in the direction perpendicular to the slot, and the connection has to be a bearing type connection because you don´t want to transfer any vertical load to the wall by friction. I agree with the suggestion of accounting for a very small allowable stress in the fastener and sizing it accordingly. I have in the past used 2 inch slots in the same way with no problems whatsoever. It is very important to specify the nut installation method to avoid overtightening. That would defeat the purpose.

BTW, This is my first post on this forum.... It seems like a great place to obtain good information.

 

[gwynn]

If specifying a connection similar to this I would be most concerned with limiting the bearing stresses along the length of the slotted hole. I would look at designing the connection with bearing stresses in the ranges allowed for rockers or pins.

I agree with panama on avoiding overtightening.

 

[hokie66]

You not only want to avoid overtightening, the bolts should be loose. Finger tighten and back off 1/4 turn. Locknuts are good or Loctite.

Welcome, PanamaStrEng.

 

[tngolfer]

I don't see a problem in a 2" slotted hole. Our office has used a similar connection to keep from loading a cmu wall. We used a an inverted angle with a slotted hole with an open end because the angle had to be installed last.