Intermittent Weld 2

[dik]

I've generally used weld spacing of:
-FOR INTERMITTENT WELDS, LENGTH SHALL NOT BE LESS THAN THE GREATER OF 4 TIMES THE WELD SIZE OR 40MM. MAX CLEAR SPACING SHALL NOT EXCEED 12 TIMES THE THINNER OF THE TWO SECTIONS JOINED FOR JOINTS IN COMPRESSION AND 16 TIMES FOR JOINTS IN TENSION.

I recently came across the following:
-FOR INTERMITTENT WELDS, LENGTH SHALL NOT BE LESS THAN THE GREATER OF 4 TIMES THE WELD SIZE OR 40MM. MAX CLEAR SPACING SHALL NOT EXCEED 24 TIMES THE THINNER OF THE TWO SECTIONS JOINED (AWS D1.1 2004 2.11.2-1).

I don't know where the first spacing came from (I've always used it, but don't know the source), but the AWS stipulation allows a greater spacing. Is anyone familiar with the first criteria? and are there any caveats about using the second criteria as long as the weld is strong enough?

For an intermittent weld, 4@12 means 4" of fillet weld at 12" centre to centre of weld group; is my understanding correct?

Dik

 

[RPMG]

Veer,

If the end-welds match the tension strength of the plate, any intermittent welds that meet the maximum spacing will be conservative and adequate.

 

[dik]

Veer:"Shall I follow the spacing for tension members, which is 36*t or 18"? for my case"

I usually don't go beyond a spacing of 12" for intermittent welds even though you can go to 18" clear. The Canadian code references slenderness ratio which makes sense. Just a personal quirk to use 12" and not clear.

The question came up because I was reviewing some drawings where the engineer had gone to 18" and before I commented, I had to know the reason for my choice...

Dik

 

[r13]

Veer07,

- Do a plan layout of the welds and locate the joist bearings, then think how the plate behaves with scattered weld support. Will it bend uniformly as in the design, or stress will be concentrated at the support points only. I think specify the welds farther apart for saving will cause you more trouble down the road. (A FEM plate model will give you better feel)

- Did you check the beam for torsion? I think the concrete slab is much heavier than the joist, thus the presence of torsion.

 

[Veer007]

Thank you RPMG...
Right, I too usually don't use 18" which exceeds 12".

- Did you check the beam for torsion? I think the concrete slab is much heavier than the joist, thus the presence of torsion.

the CFC joists going to support deck with 4" concrete slab. This may reduce torsion, However, I can't decide beam profile which is sufficient or not as this was designed by EOR. Also, I can insist on any changes need to be performed for better work.

Thanks in advance!!