Welding in the 'k-area'
Welding in the 'k-area'
(OP)
I am designing a welded moment connection using Australian Standard AS4100.
Common practise in Australia is to fully weld continuity stiffeners at moment connections to the column flanges and web. However, the US company we are working with on our project have expressed concern about welding on the 'k-area' of the column (apparently AISC recommends against it).
Is this a recommendation only or is it mandatory when designing to US design codes? What do the US welding codes say on the matter?
I have not seen anything like this in the Australian Standards and am reluctant to clip or scallop stiffeners for two reasons:
1. it is harder to maintain continuity of welds through the scallops
2. surface preparation and painting of the steelwork around the scallops may be compromised - i.e. harder to paint in and around scallops.
Has anyone come across a requirement to avoid welds on the 'k-area' in the Australian codes. How do US fabricators get around the two issues above?
Common practise in Australia is to fully weld continuity stiffeners at moment connections to the column flanges and web. However, the US company we are working with on our project have expressed concern about welding on the 'k-area' of the column (apparently AISC recommends against it).
Is this a recommendation only or is it mandatory when designing to US design codes? What do the US welding codes say on the matter?
I have not seen anything like this in the Australian Standards and am reluctant to clip or scallop stiffeners for two reasons:
1. it is harder to maintain continuity of welds through the scallops
2. surface preparation and painting of the steelwork around the scallops may be compromised - i.e. harder to paint in and around scallops.
Has anyone come across a requirement to avoid welds on the 'k-area' in the Australian codes. How do US fabricators get around the two issues above?






RE: Welding in the 'k-area'
Usually continuity plates are designed to transfer beam flange forces through the column to another beam or to the web of the column. In these instances the welds along the column flange and web are sized appropriately to transfer these forces taking reductions for the "clipped" continuity plates.
I don't think may would worry about painting as the connections are usually buried within the building are are not exposed to the elements.
RE: Welding in the 'k-area'
Dik
RE: Welding in the 'k-area'
RE: Welding in the 'k-area'
RE: Welding in the 'k-area'
I want to say that some of these details were developed for AISC post Northridge/Kobe EQ.
Again, this is based on memory and only my 2-cents as someone who follows AISC and recommends one to follow them...
RE: Welding in the 'k-area'
RE: Welding in the 'k-area'
So basically even if welding in that region were fine why would you make them fabricate and weld for that geometry?
RE: Welding in the 'k-area'
1. No mention of not welding the k area in the Australian Standards.
2. The fabricator has advised no additional cost or time impact. The stiffener is clipped and then the small void filled with weld metal during welding.
3. The Client specifications state that all ratholes shall be filled.
4. The project location is hot/tropical and non-seismic. The structure is not exposed to fatigue loading.
5. The structure is outdoors and close to the ocean (higher corrosion risk). There is a risk that painting and surface preparation in and around any void left will not be possible or will be compromised. There is also a requirement for all welding to be continous and it could be tricky continuing welds through ratholes left.
It is correct that the stiffeners are still structurally adequate with the rat holes. However, like most things engineering, this particular issue stopped being about strength a long time ago! Thanks for all the responses!
RE: Welding in the 'k-area'
In your situation, if galvanized, they are probably best left open. If other protective coatings, then close them. But if there is a specification requiring continuous welding, you may not have a choice.
RE: Welding in the 'k-area'
Dik
RE: Welding in the 'k-area'
Here are some links with AISC information on welding in the k-area
K-Area Welding in 2/14 Modern Steel:http://www.modernsteel.com/Uploads/Issues/January_... . Synopsis: welding in the k-area is discouraged but not prohibited.
AISC Advisory Statement on Mechanical Properties Near the Fillet of Wide Flange Shapes and Interim Recommendations, January 10, 1997: http://www.modernsteel.com/Uploads/Issues/February... The entire issue of Modern Steel is at this link (slow download). The information on k-Area welding is on page 18 (page 20 of the pdf).
The Commentary to AISC's specification has some information in Comm.J10.8 on page 362. The entire spec can be downloaded at: http://www.aisc.org/content.aspx?id=2884#spec
You might be able to appease your US partners by inspecting for cracks with MT after welding and/or using fillet welds if you aren't already.
RE: Welding in the 'k-area'
RE: Welding in the 'k-area'
RE: Welding in the 'k-area'
RE: Welding in the 'k-area'
It seems to me that that is going to be a very difficult detail to weld full, and get at during welding to get good penetration, particularly into the stiff. pl. And then, there is some chance that you will not get a good weld to the col. fillet from both sides, at the root, even if this is done in the shop. If they’ve clipped the stiff. pl. to miss the radius, they probably have to bevel the clip so they can get weld pen. to the pl. If they had actually fit the plate to the radius, a tedious process too, they could at least apply a continuous fillet weld. So, they haven’t saved any time or money either way, and end up with a crappy weld detail.
The fabricators like the clipped corner because that stiff. pl. is easier to fit-up, and they don’t have to weld into that corner which always leads to tri-axial stresses, compound residual stresses and the potential for an inferior weld detail/condition at that corner. You really must be very careful welding around the edges of these pls. too. They almost always leave notches at the vert. edge corners of the stiff. pls. where the weld face meets the edge corners.
High likelihood of weld defects, tough to inspect properly, tri-axial stress in a corner, combined residual stresses (rolling and welding), are just not a good condition. But, I have done it. The primary Northridge failure detail was different than yours. But, many of the failures were due to crappy weld details in the fillet area, a very stiff area of the member which makes it more susceptible to any defects and high combined stresses, and your detail does have that in common.