PEMB Tie-Rod A36 Bar Splice 1

[BSVBD]

PEMB with a 120' clear span. Hairpins will not work, so i'm using tie-rod.

I've done these in the past, and, therefore, i do plan on using a flat-bar, field-groove-welded splice.

BUT! I'm always considering if there are innovative ways of doing things.

The only thing i'm finding "readily" available on the internet is splices for rebar.

Any (new) suggestions?

 

[msquared48]

I've used section of angle of varying length embed in the slab with the tie rods welded to it in the inside curvature. You can stagger the splices as needed too.

Mike McCann, PE, SE (WA)

 

[BSVBD]

ms - thank you!

I'm giving the general the option of flat bar or angle.

I like the angle idea. It will likely provide an easier weld position.

 

[hokie66]

I have used mechanically spliced reinforcing bars. And I don't like embedding the ties in the slab.

 

[BSVBD]

hokie,

How do you anchor / fasten the rebar to rigid frame base?

Where do you place the ties?

 

[KootK]

I prefer the angle over the flat plate too. Among other things:

1) The angle itself is considerably stiffer flexurally which helps with eccentricities.

2) You can get a pair of welds on the rebar that will be more or less concentric to the rebar.

Some folks like to place the ties beneath the slab rather than in it. Depending on your detailing, this may mean that the ties get attached to your frame support pier rather than the pier itself. I've heard engineers express concern that future modifications to slabs on grade mean that there's potential for your very important ties to get inadvertently severed. It's also a bit difficult to predict slab on grade cracking in the vicinity of the ties if they're working at all hard.

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.

 

[KootK]

Also, what's your objection to mechanical splicing in this situation? Getting the lengths right?

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.

 

[BUGGAR]

Do you have welding procedures in place, or make them for each job?

 

[msquared48]

With a 120 foot span, the kick can be a lot. I have used a separate grade beam containing the tension tie steel below the slab in many instances too. This is particularly needed in large horse arenas where there is no slab and you have to get well below the level of use.

Mike McCann, PE, SE (WA)

 

[hokie66]

BSVBD,
When I have done it, the ties were between the concrete piers, not between the steel columns. Placed below the slab, with appropriate corrosion protection.

But if you use tension ties, you need to be sure that there are not going to be future modifications which will interrupt the ties. So in industrial buildings, I would always design the footings on each side to take the thrust and moment.