Grouting needle beam holes 2

[Klitor]

Hi fellas,

I need to cut a 5m wide opening in existing precast wall.
Wall is 20cm thick (7cm concrete + 6cm styrofoan + 7cm concrete)
I suggested temporary shoring using needle beams spaced 70cm or so and "jacked" via regular steel post supports .
Do i need to specify some sort of special grout around beams before jacking the wall - I suspect contractor will probably cut larger irregular holes - and I am worried about wall cracking or wall layers separating.

Thx.

 

[KootK]

I'm not sure if I should be grouting but I haven't been. At the spacings that I use needle beams, the stresses would be pretty low. And I would expect the contractor to cut the hole a good deal more square than your sketch would imply.

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.

 

[jayrod12]

They've always used a saw to make the cuts when I've seen it, they're basically square each time. I don't think I've ever seen a situation where they've just hammered a hole through the wall.

I haven't spec'd grout either.

 

[PEinc]

The needle beams in the attached photo have all been grouted. I would definitely grout the hole, or at least drypack between the top of the needle beam and the wall.

http://www.PeirceEngineering.com

 

[KootK]

Now that is a needle beam. I'm going to keep that photo to show folks when they bitch about my mickey mouse stuff.

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.

 

[Klitor]

PEinc thats a hunk of steel - I must admit, I cant even follow what it is - It looks like needle beams have been cut and remaining parts welded with stubs to transfer beam below? Could you elaborate a bit

Regarding grouting - Did you use some sort of special grout-like product (Sika etc.)?

Kootk, jayrod thanx for the input - I guess I did exaggerate with sloppines of the hole being made. I am a bit worried since the wall is composite (conc+styrofoam) that layers will separate.

 

[KootK]

If seperation is a primary concern, perhaps you could through bolt a pair of horizontal channels to the wall and then install needle beams up to the underside of those. I suspect that's unnecessary however.

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.

 

[PEinc]

Klitor, micropiles supported two cap beams that ran through stacked, overlapping, cored holes in the existing wall at the ends of the planned opening. The two cap beams supported two transfer beams, one against each side of the wall. The needle beams ran through cored holes in the wall and were connected to the transfer beams with stub beam seat. The cored holes were specified to be filled with non-shrink grout around the wall-penetrating beams. I designed the micropiles. The beams were designed by the project engineer.

www.PeirceEngineering.com

 

[Klitor]

Just a follow-up if anyone finds useful.

I ended up trough bolting some channels for extra safety.

Contractor cored round holes for needle beams and plugged wooden wedges inside.

 

[PEinc]

Thanks for the update. Looks like it worked!

http://www.PeirceEngineering.com