Concrete stair and landing detail

[gagne73]

I have a concrete stair/landing detail that I can not figure out.

see the attached, my landing spans side to side. I have seen this detail used a few times, but I am not a huge fan of it due to the cold joint locations, meaning the dowels are in direct shear in those locations, and those same dowels are used as the tension reinforcing across the landing. I can not come up with a better way to detail this. does any one have any suggestions? I can only span this landing side to side.


alternate question: I have a long stair that is between two concrete walls the full length. Instead of spanning the stairs full length, I was hoping to span them side to side, similar to what I was talking about above. My question is, do you think it would be reasonable to request a keyway along the length of the stairs? I can't imagine the contractor will be trilled about trying to locate that keyway properly in their formwork, but again I dont want to count on ONLY the reinforcing steel being in direct shear to stop these from failing.


I would appreciate any and all responses, this is getting fairly urgent.

fyi, I have already looked extensively through the old posts and cant find anything (I saw one that looked similar but the attachment no longer works, so It doesn't help)

 

[jayrod12]

Why the need for a cold joint? Couldn't they pour it monolithically or provide a keyway into the beams?

In our office if we were told the landing and the stairs HAD to be poured after the adjacent beams then we would hope to cast in a bearing angle, with nelson studs or weldable rebar into the beams, on each adjacent beam during their pours giving additional bearing area for the stair landing. You could theoretically design either epoxy anchors or mechanical expansion anchors (I do not recommend expansion anchors based on personal preferences) that could support a bearing angle.

With post installed anchors you could do this same detail for your stairs allowing them to pour the adjacent walls with a smooth face and then come in after and align the bearing angle.

Just a thought.

 

[BAretired]

Could use embed plates on each beam with welded angles into slab.

Alternate question: The contractor should have no problem placing a keyway inside his wall forms. Why should he object?


BA

 

[gagne73]

Thanks for the reply,

The problem with pouring it monolithically, is that I have just pushed this same issue further down the line. this landing extending out, then 90 degree to the next flight, and then another 90 off that next landing

I have though about the same in anchoring angle for bearing using epoxy (I too dont like the mechanical anchors) I think I am going to get them to put in a keyway, it may be tough but I m not sure any alternative will be easier

 

[gagne73]

BAretired,

in my opinion we in Saskatchewan (Saskatoon for sure) have a large problem with contractors having the attitude of 'well this has worked forever, why should we change it now..', even though these things usually haven't worked forever, they just weren't the ones that were called in after it failed, that is usually us. We have weekly issues with them not wanting to do things that we have specified, even though the things we specified are still much easier than what is done in the rest of the country. I guess that is what we get without having to account for any seismic, and having pretty good soils. contractors here dont like even remotely complicated details.

my other respone was dorected at jayrod before I read your post, but again, I think i will tell them to suck it up and do a keyway for both parts. I neglected to say in my sketch that the landing is 8" htik, so I should be able to do a 1x4 keyway(top of keyway flush with top of slab). that in combination with the dowels should be adequate