New Steel Joist To Existing 2

[BSVBD]

Please see attached…

We obviously cannot erect this new OWSJ to existing as is shown in the attached with a pocket at each end.

Suggestion #1 - Provide a steel angle on left / south end, through-bolted to existing. I do not like this idea as I feel the axial load would be imposed to the 4” wythe only. Please comment.

Suggestion #2 – Remove (24’ lineal feet of) existing masonry courses, on left / south end, down to joist bearing, provide solid grouted bearing surface, with joist bearing plates.

Any other suggestions?

Thank you!

 

[Triangled]

manufacture in halves with moment connection

 

[Triangled]

attached

 

[BAretired]

I agree with using a bolted moment connection at midspan.

BA

 

[JAE]

We've done the moment connection as well. Contact your local joist manufacturer and the can design it as part of the shop drawing and fabrication process.

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[wannabeSE]

When you talk to the joist manufacture, talk to them about the distance between the last web member and the bearing at the CMU (unless you intend to remove the brick veneer to clear the web member).

 

[KootK]

@BSVBD: My thinking is actually pretty close to yours. Don't be deterred by the red wine stains.

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.

 

[BSVBD]

Triangled... I admit... at first, I thought you were joking. I've never seen this. Great idea! Simple! How long has this been around?

Can any of you tell me what "up-charge" you've experienced? I will contact the vendors whom I typically deal with.

Can this be erected with one crane? This is a very small project of (10) joists.

Thank you all for your input!

 

[KootK]

The craning/shoring part was exactly my concern with the two piece. There's a fair bit of fussy handling involved with that method. I've done it but only in rather extreme cases where it was pretty much unavoidable. In practical terms, I suspect that you'll pretty much destroy the entire left side brick parapet when you make your joist connection over there. With that being the case, just destroy it before hand and find yourself with a more conventional erection scenario. You planning to get your diaphragm shears into the walls via joist rollover resistance?

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.

 

[BSVBD]

Koot... We MAY still demo the parapet yet. But, we'll let the G.C. make that decision.

Regarding the crane, it has already been decided that a single crane with a split hoist line (two lines) can be used, IF a crane is even necessary for these considerably light 18' joists.

As far as diaphragm shears, the added lateral forces applied to this small addition to this CMU building are negligible.

 

[KootK]

Given the scale of this, I wonder if joists are even the way to go. Perhaps you could use some W12x14 with 4" dapped ends and a BSVBD designed field moment connection at the 1/4 point. That would take care of erection and the last diagonal issue. Plus you could put some RTU's on it painlessly in the future. For something so small, I'd have to think that most of the cost is tied up in the masonry fussing anyhow. The moment connection in the joist and any oddness near the seat are going make these quite non-standard joists anyhow. That may well neuter their usual competitive advantage.

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.

 

[JLNJ]

As usual, Koot beat me to it, but my first thought was to use beams.

It seems to me that you'd need many, many joists to make them worth the while. Maybe you can even slide one end through and make them all up on one piece.

 

[JAE]

Here is an example of a joist splice detail:

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[kipfoot]

I'll add my vote for a wide flange section, though that's not what you asked about. I'd consider making the hole in the north end (where there's less interference) so you can poke the beam through and slide it back to a bearing pocket on the south end.

For the 24' you could do this for every other member and have a header in between to reduce the masonry demo. The sketch shows what I mean for a 4' deck span.