Wood as wind girt? 3

• May 12, 2020

• #2

BAretired

Structural

Nov 16, 2008

10,876

Span is 20', a long span for a 5.5" deep LVL. Check stress and deflection. Why would you think it could be reduced?

BA

 

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• May 12, 2020

1
• #3

JAE

Structural

Jun 27, 2000

15,483

I think what you are suggesting is that the little clips on the small studs would somehow "fix" the studs such that they are cantilevering off the floor and helping the sill beam.
I don't think this would really happen.

The beam would have to span the 20 ft. and take its share of the wind load from the 1/2 stud height below and whatever window span occurs above.

 

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• May 12, 2020

• Thread starter
• #4

palk7 EIT

Structural

May 12, 2020

150

Yes I thought if those clips help in fixing the studs there, yeah I need to check for the full span.

 

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• May 12, 2020

• Thread starter
• #5

palk7 EIT

Structural

May 12, 2020

150

Should Wind loads be factored by 1.5 like a Live load?

 

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• May 12, 2020

• #6

JAE

Structural

Jun 27, 2000

15,483

Depends on the code and the design method you are using. In my neck of the woods (US) I've never factored live loads by 1.5.
For wood design I use ASD which provides for allowable stresses in wood members and connections. There is no load factor on that.

Can you explain a bit where you got your 1.5 factor? Is this a Canada code?

 

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• May 12, 2020

• #7

BAretired

Structural

Nov 16, 2008

10,876

Use factored loads for strength check, unfactored loads for deflection check.



BA

 

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• May 12, 2020

• #8

BAretired

Structural

Nov 16, 2008

10,876

JAE,
The Canadian code uses only one method of analyzing structures. We called it Limit States Design in my day, but it may have a different name now. The load factor for live load, including wind was 1.5. There is no longer a Working Stress Design (WSD) permitted in the Canadian code.



BA

 

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• May 12, 2020

• Thread starter
• #9

palk7 EIT

Structural

May 12, 2020

150

Yes, agree with BAretired

 

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• May 12, 2020

1
• #10

BAretired

Structural

Nov 16, 2008

10,876

palk7,

The notion of using 3' long studs, fixed at the base is not wrong, provided that the rim beam is capable of resisting the applied moment, but you cannot use little angle clips to attach them at the base. Developing moment connections with conventional wood framing is possible but is not commonly done.

BA

 

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• May 12, 2020

• Thread starter
• #11

palk7 EIT

Structural

May 12, 2020

150

O.k, just to know, what is the role of infill studs is it there just to stiffen the exterior sheathing or does it act as a transfer medium to transfer the wind pressure to the girt?. If it helps to transfer then, that connection point of the stud to girt (above) or the stud to the bottom plate which in turn is connected to rim joist +LVL below must be designed for a horizontal point load at that connection so in that case would that point load be the spacing of studs * height of exposure?

 

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• May 12, 2020

1
• #12

KootK

Structural

Oct 16, 2001

18,298

palk7 said:

O.k, just to know, what is the role of infill studs is it there just to stiffen the exterior sheathing or does it act as a transfer medium to transfer the wind pressure to the girt?

Click to expand...

The infill stud perform both of those functions.

palk7 said:

If it helps to transfer then, that connection point of the stud to girt (above) or the stud to the bottom plate which in turn is connected to rim joist +LVL below must be designed for a horizontal point load at that connection so in that case would that point load be the spacing of studs * height of exposure?

Click to expand...

Yeah, each infill stud would deliver a little reaction, top and bottom equal to [height/2 x spacing x design wind pressure]. For your girt span and stud spacing, most engineers would just approximate all those point loads a uniform, lineal load equal to wind [height/2 x design wind pressure] to the girt and the diaphragm below.

 

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