Hairpin in Metal Building Slabs

[TimmyH76]

How do you deal with lateral forces (thrust) in a metal building frame that is at the corner of the building? With the center frames there is plenty of room to put a hairpin. Is the only option a tie between the columns? Thanks for the insight.

 

[Lion06]

What exactly is a "hairpin"?

 

[ash060]

You can use a hairpin to resist the lateral forces. If you check AISC's Base Plate Design Guide, they will have an example.

A hairpin is a piece of rebar bent in the shape of a hairpin to resist thrust forces. They are usually found in slabs and foundations

 

[TimmyH76]

What about at the colums at the corner of the slab? Usually the hairpins are bent in the shape of a V, this doesn't work when its close to the edge of the slab.

 

[jike]

In the corner of a building, where you have a column pier and intersecting foundation walls (all cast monolithically) resist the thrust by the rebar that you place in the top of the foundation wall. You should be able to do a similar type of thing with the grade beams in a thickened edge type of foundation.

Please note that the use of hairpins is typically for the smaller, shorter span metal buildings.

 

[DaveAtkins]

I agree with jike. Sometimes it means I put three or four rebar at the top of the foundation wall, instead of just two. And make sure the rebar is hooked at the outside corner; otherwise it will not be developed.

DaveAtkins

 

[JD2]

I agree with jike and DaveAtkins, I have used this detail. Another detail I have used is instead of using a "Vee" shaped hairpin, straighten out one leg of the "Vee" so that it is parallel to the outside face of the grade beam (the other leg is still at a 30 or 45 degree angle).

 

[UcfSE]

We use the same as JD2, straighten one leg of the hairpin at the corners.

 

[valleyboy]

You could use lightweight gable frames with vertical bracing to achieve in-plane stability - in this case there will be no horizontal shear at the base.

If you specifically need to design the gable frame as a portal (for example if you are designing for future extension), you could simply design the foundation to resist this horizontal load in addition to the vertical load.

VB