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Shear Wall Detailing

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Contraflexure74

Contraflexure74

Structural
Jan 29, 2016
147
Hi,

I have a steel frame which is braced along one elevation with a 215mm masonry wall. The steel column is a 203UC 46.

I want to build the blockwork tight into the web of the column but the mason is saying its difficult to cut off such a small amount off of the block edge to run the blockwork tight into the column web.

I am also shot fixing walls ties at 450mm crs to the web to tie the masonry to the steel column.

The only thing I can think of is to use a 140mm wide block at the end of the masonry panel which sits between the column flanges, then pack with mortar out to the column flanges for a tight fit.

Anyone come up with this problem before?

John.
 
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Have you considered finishing the between the end of the wall and the steel section in concrete, stopping the wall slightly short of the flanges.

Then fill the entire area between the flanges/web with concrete, boxing it out as required. Weld some starters to the web to lap with the horizontal reinforcing.

Even if you do manage to get the block to work its likely to leak the block fill as its going to be difficult to seal, and could result in voids in the wall.

 
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In your situation, you probably don't need connection between wall and columns. You just need connection between wall and eave beam. the NCMA tek series, available online, has some good example details.

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.
 
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Hi KootK,

I can't make a connection between the wall and the eaves beam as the Arch has a continuous short window 700mm high running the length of the building above my shear wall along grid B.

John.
 
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In that case, you'll probably want some kind of steel girt/strut member running horizontally at the elevation of the bottom of the short window to transfer shear loads out of the columns and into the shear walls. Your columns would need to be designed as cantilevering above that elevation for lateral loads.

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.
 
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Hi Kootk,

Could this be an 100x100x10 angle bolted face down between columns and bolted to the block every 600mm. Columns are 5m centres. Not sure how I would design this.......?

The Arch will not want to see anything obstructing the window.

regards,

John.
 
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No it would likely need to be significantly more substantial than an angle.

Koot is suggesting providing a girt (likely a SHS) to act as a collector at the top of the wall. This will allow you to connect the top of your shear wall to this girt, as well as making the window installation easier.
 
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JF said:
Could this be an 100x100x10 angle bolted face down between columns and bolted to the block every 600mm.
Click to expand...

It certainly could so long as the numbers work. You might also be able to install something behind the masonry rather than on top of it. With that, however, you're likely to have eccentricity to deal with at the column connection. While you're not planning to use a wide flange, this NCMA tek may provide some useful detailing tips: Link

Are the CMU walls themselves designed to span horizontally between columns then?

JF said:
Not sure how I would design this.......?
Click to expand...

Same as you've been designing everything else so far. Start with a free body diagram showing how lateral loads make their way out of the roof diaphragm and into the block walls.



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.
 
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Hi Kootk,

Yes the walls have been designed to span between the columns.

I could be in trouble here as the steel is being fabbed in the shop at the mo.

John.
 
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The bond beam at the top of the wall could also be the drag strut member if you can find a way to tie it robustly to the columns at the ends. I've suggested a detail below. This obviously would go part and parcel with your plans for tying the wall into the columns in general.

Capture_c38jc5.jpg


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.
 
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Hi Kootk,

Thanks for that. Would the following detail work or is a channel normally used due to the compression force. I calculate the force in the girt to be 4.6kN.

If the wall is built tight to the column web does the girt become redundant or am I totally missing the point?

I also have ties shot fixed at 450mm centres on both sides of the column web to tie the masonry to the steel column.

John.
 
 http://files.engineering.com/getfile.aspx?folder=1d0fd755-0626-4ad4-b9b1-728ed2ec8e9e&file=Shear_Wall.pdf
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JF said:
Would the following detail work or is a channel normally used due to the compression force.
Click to expand...

Should be fine so long as all of your connections are designed properly.

JF said:
If the wall is built tight to the column web does the girt become redundant or am I totally missing the point?
Click to expand...

Some of each. You're correct in thinking that, with no girt, there's still a load path there (columns lean on block). The trouble, in my mind, is a) assessing that path and b) constructability issues surrounding the mason's ability to build it snug up to the column web. In my opinion, a drag strut / girt member of some sort is required.

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.
 
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Just thought of something Kootk.

What about using a timber that is bolt fixed to the top of the wall (at 450mm crs) and secured tight into the column webs, possibly a 75x150 (timber grade C16). This could be sorted on site without any steel fabrication and the load transfer into the top of the shear wall would be distributed. The timber could be treated if we were worried about it's design life.

John.
 
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Works for me so long as the timber member is one piece between columns and is connected to the columns to transfer strut axial loads as the steel members would have been.

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.
 
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