HSS End connection welded from three sides only 1

[FOX89]

Hi,

i have the following connection which is RHS250x150x12.5(beam) directly welded (CJP) to SHS180x180x12.5 / SHS150x150x12.5(column), the angle was provided as a seat and it was supposed to be removed after welding three sides of the beam then weld the lower side.

Now i have been told that the angles have been welded 8 or 10 mm (to the column) by mistake and they CAN'T remove it ! is that acceptable ? what should i do as a recovery and how can i check it ?

 

[bowlingdanish]

Is there any uplift on the beam or is this part of a lateral stability system? If not I would say it's fine as is, assuming you have enough vertical weld for shear. If there is non trivial uplift or it is a moment frame it could potentially get a bit messy.

 

[FOX89]

it is a part of a moment frame !

 

[KootK]

Because of column wall flexibility, most of your moment was going to be transferred through the vertical welds anyway, even in the original design. As a first step, I'd just see if it would work using the vertical welds only.

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.

 

[FOX89]

kootk;

shouldn't the moment be transferred by the upper and the lower walls, since the moment distribution will be the maximum at these walls

 

[racookpe1978]

The original joint was going to be fillet-welded all-around, with complete penetration of the 10 mm thick tube steel, with backing (??) for a angle-prepped joint, right?

Each angle iron is 100x100x10 x 170 mm (long), so weld all-around every angle's edges with a 8 mm - 10 mm fillet. You will end up with slightly more weld metal, and that weld metal is on average further from the joint's original shape, so the total moment resistance to twisting is greater.

Leaving as-is (with the short and very irregular) "tack welds" - which few welders take seriously for penetration, length, nor quality! - is not acceptable.

 

[KootK]

shouldn't the moment be transferred by the upper and the lower walls, since the moment distribution will be the maximum at these walls

No. Because of column flexibility, the side walls will be the stiffest place to transfer moment. Do you have the AISC HSS connection design guide or the CIDECT design guides? They both cover this kind of connection. Are you required to transfer the full Zx x Fy moment here?

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.

 

[SAIL3]

I agree with Koot, if the bm is as wide or close to the width of the col....

 

[Brad805]

Can't remove or do not want to? If this is an industrial plant and this work requires a hot ticket, then I get it, but if not I would ask for some pictures to justify why it cannot be removed. Are you getting paid to investigate this?

 

[hokie66]

That weld at the top is not going to do much without a plate across the column.

 

[SAIL3]

picking up on hokie's comment, the OP may be able to add ,in the field ,an oversized cap pl on the col and extend it out over the bm which would give a 3-sided weld if it is required....I always try to close-off the ends of HSS members as standard practice.....

 

[FOX89]

Racoopke, the uploaded pic is the original design .. it was supposed to be welded full penetration all around .. that angle is a temporary seat ( but it's not anymore because of the 8 mm fillet weld instead of tack weld).

Brad805, the fabricator welded this plate with 8 mm weld by mistake and these column ( too many) have been installed , they are at the edge of a tower elevated at 250+ meters. Removing the plate and fixing the damaged column will be hard, time consuming and dangerous.

Kootk, I am reviewing the CIDECT and it is mentioned here that when you have a widths ratio = 1 ,it will be stiff enough to transfer the loads through the walls parallel with the column, but does it means that these walls will never transfer the moment ! If so , should I just fillet weld the angle to the beam ?

The moment is reversal at this connections, with presence of tension and shear on both axis.