HSS Weld and Connection

[streng9999]

Hello.

I am connecting a HSS to a 6" concrete slab using mechanical anchors.
My initial design approach was to resolve the entire moment demand into a force couple on the two anchors going into the slab mid-depth and just use the distance between the anchors and the bottom of the connection plate (d) as the moment arm but I'm not getting close to the required capacity. The tension demand is ~20 kips per anchor using that approach.
I'm trying to add additional anchors connected to the bottom of the slab but unsure as to how the overall connection would work as the concrete failure planes for the two sets of anchors would overlap.
I'm looking for different connection ideas or approaches if anyone has experience with this.

 

[KootK]

...but unsure as to how the overall connection would work as the concrete failure planes for the two sets of anchors would overlap.

I would have that same concern. And, if dealt with properly somehow, I suspect that the result would be the underside anchors not helping that much.

I imagine that an angle wrapped over the top of the slab would be a spatial problem?

 

[KootK]

Also, is this level slap or some weird, sloped thing? Your sketch kind of suggests the latter.

 

[streng9999]

Thanks for replying.
It's all level - my sketch is a little rough.
I was thinking of re-orienting the anchors which would allow more anchors in and a larger moment arm (x) to help with the demand per anchor.
But still an issue with anchor pullout/concrete breakout.
Through bolting might help with the both but hard to find an approach that quantifies it.

 

[DaveAtkins]

Can you embed another tube or a wide flange in the concrete slab, extending it back some distance (say two or three feet)? Then put studs off each side of the tube or wide flange. A much bigger moment arm.

DaveAtkins

 

[KootK]

I like Dave's idea very much if that would be viable.

 

[streng9999]

Thanks Dave and KootK - site constraints made that option unfeasible and I ended up going another route by using a steel member in the vicinity to act as a support.

I had a question about the HSS beam - Vert HSS weld.
I sized the smaller beam HSS (4x4) such that the workable flat of the larger HSS6x6x.375 (~4.25" workable flat) is larger than the out-to-out dimension of the smaller HSS.
Can I count on the full 4" length for all legs of the fillet weld even with the radius?
AISC Manual doesn't say anything on the matter but wanted to get other's thoughts on it.