Hollow Core Chord Reinforcement

[Galambos]

Can someone explain how hollow core chord reinforcement is achieved when bearing on light gage walls. I dont have a masonry bond beam to take advantage of. any ideas?

does the end cell on one edge get reinforced and grouted completely? how about the end-of-plank condition?

thanks ahead of time.

 

[Galambos]

i should add that this is a non-topped system in SDC C.

 

[jike]

You could cut out the top of the plank and grout rebar in. This can be done in both directions.

 

[Teguci]

One option is to cast a concrete beam around the perimeter of the plank to place your chord steel (ref Fig 3.8.1.3 PCI Design Handbook 6th ed).
For chord steel, I prefer to develop the bars around the corners with full lap lengths.
This gives you a full rubber band effect around the perimeter so you don't have to rely on unreinforced concrete friction to maintain your chord steel at the ends.

 

[spats]

Precast concrete structures are required to be properly tied, and meet the requirements of ACI318 Section 7.13.3, which references Section 16.5 - Structural Integrity.

See also PCI Design Handbook (5th Edition), Section 3.10.2.

 

[UcfSE]

You can provide a continuous bar(s) around the perimeter and cast them inside a secondary pour. This pour would be the height of the plank and extend to the outer edge of the wall. Wall framing would stop at bottom of plank and pick up again on top of the plank or secondary pour.

 

[haynewp]

If the hollowcore is sitting on a structural tube along the top of the stud bearing wall, you might can make this tube continuous and serve as the chord.

 

[jheidt2543]

Just a thought, since these plank systems are grouted together, even when there is no topping, wouldn't addition of weld plates provide the necessary tie? And, when the plank bear on a Lt.Ga. stud wall, using a rolled steel angle on the top plate to connect the weld plates to should also work.

Years ago some engineers relied on the dead load friction of the plank on a masonry wall to take the load, not that I'm advocating that, but it was done many times.

 

[rdbse]

How do you plan to connect the hollow core to the light gage walls? I am not sure if this is part of your question.

As others have mentioned, you can place rebar in the cut end cores and grout. You might consider a continuous angle with headed studs welded to the top track. The grout will tie the slab to the angle and wall.

 

[jheidt2543]

rdbse:

Sorry, I may not have been clear. The hollow core slabs are cast with a weld plate in the bottomwe bearing side. The weld plate is welded to a continuous rolled steel angle that is welded to the top plate of the steel stud wall.

 

[Teguci]

Sounds like the steel angle can act as your chord steel, just make sure it is continuous all the way around.

You should probably check the eccentricity of the angle to the plane of the hollow core slab for additional bending on the planks (this is probably pretty picky).