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

 

[JAE]

Perhaps the 12 times was a more conservative application by an engineer and it became "tradition"?

For my interpretation - 4@12 means what you suggest in your last line.

 

[dik]

Thanks... found the following in Canadian CSA code:

-FOR INTERMITTENT WELDS, LENGTH SHALL NOT BE LESS THAN THE GREATER OF 4 TIMES THE WELD SIZE OR 40MM (1-1/2”). 25% MIN OF THE JOINT SHALL BE WELDED. MAX CLEAR SPACING BETWEEN WELDS SHALL NOT EXCEED 12 TIMES THE THINNER OF THE TWO SECTIONS JOINED OR 150 MM (6”) (CSA W59 12.4.14 (f)).

It's a little more restrictive... and has 12x t or 6".

Dik

 

[Veer007]

HI DIK,

For cont plate which welded on beam bottom or top, We usually use 2@12 for 1/4" size weld, is it okay? per condition 12 times shall not exceed means, if the plate is 3/8 thick, we don't provide spacing more than 12*3/8=4.5" or 6"??????????

Can you please refer me to which section from CISC that you have found out.

Thanks in advance!!

 

[dik]

That's in CSA W59 as noted, and for cyclically loaded parts... I've found another part that's less restrictive, for static welds also in W59 11.4.13.3... I missed this and up to that point, the only one I could find... Something broken... I cannot upload the file either as a *.pdf or as a *.png.

Dik

 

[Veer007]

above my concerns are correct or not?

Thanks in advance!!

 

[r13]

Veer07,

2@12 means 2" weld length at 12" center to center space, the clear spacing therefore is 12-2=10", which is greater than either code permitted for 3/8" plate. (CSA - 12t or 6"; AWS - 24t)

 

[dik]

Thanks... the portion of the code I was looking at was the wrong one... for cyclical loading... I found the correct one.

Dik

 

[r13]

OOPs! Veer07 you should feel better now, if your design was for static loading only.

 

[r13]

Veer07,

I did a quick research on this subject, AWS stays the same as stated 24t (D1.1 section 2.11.2), and a quote from the Indian code,

The clear spacing between the effective lengths of the intermittent welds should be less than or equal to 12 times the thickness of the thinner member in compression and 16 times in tension; in no case the length should exceed 20 cm.

You shall do a search on CISC to clear the confusion.

 

[dik]

Thanks, gentlemen... all is fixt. The CSA W59 clause is 11.4.13.3

Dik

 

[Veer007]

Guys if core slab supported on the plate, can I go with 2@6 for safer side?, as I have static loading only. Below is the snap.

Below is dik stated..

Thanks in advance!!

 

[r13]

Since this is a roof structure, if there is a chance the weld will be exposed to the weather and collecting water, you shall consider continuous weld. If protect from weather, and passing strength calculation, it can be done as you have proposed, but I don't really follow your design, to me it is a risky business to rely on a plate to support roof elements, you shall think other way to do it.

 

[Veer007]

Above is the EOR option, he won't like to change this as it affects ceiling clearance, also the continuous weld is not favor for my fabricator, he needs economical weld moreover, Now I'm going to scratch my head....lol

Thanks in advance!!

 

[dik]

The above is for cyclical loading the section prior to it is for static loads and is not as restrictive. I tried to post it, but the site would not allow me to upload the scan for some reason. I'll try again. Worked this time.

Dik

 

[r13]

Is the EOR a structural engineer?

 

[dik]

yes

Dik

 

[r13]

dik,

Sorry. The question was for Veer007, since I felt the design was odd - slab and joists supported by a plate stitch welded to the floor beam, quite a few thing can go wrong easily.

 

[dik]

apologies, then

Dik

 

[Veer007]

Yes, he is a structural engineer, I asked number of times to change this, but he didn't.
Any words on the weld detail I proposed? Shall I follow the spacing for tension members, which is 36*t or 18"? for my case

Thanks in advance!!