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Design of RC Cores

Design of RC Cores

(OP)
What is everyone's approach to RC cores. I normally build up the core in RAPT and design for Axial Load and Bending. I change the tension controlled and compression controlled reduction factors down to 0.4 and 0.3 except when I provide compression ties to the vertical reo, then I keep the factors at 0.8 and 0.6.

Regards

RE: Design of RC Cores

Depends on the height of building and if I am including coupling walls, but I see nothing wrong with your approach.

http://www.nceng.com.au/
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

RE: Design of RC Cores

What effective length do you input into the column module of RAPT?

RE: Design of RC Cores

(OP)
I don't. The whole assessment on whether a wall panel is slender or not is something that I assess as I go along. Generally it's not critical but it does become critical at some thin door jambs between openings. At those locations I assess the slenderness on a case by case basis. Or if there is a large void adjacent to the core where the restraint is lost.

The reason I ask is that I see people ripping wall forces out of etabs and assess each panel one by one. I have no issue with doing that I'm just a little concerned by the coarseness of the FE meshing. You pull forces out but don't get the smoothed design stress interaction. Like with a ram concept floor model, you don't design for the peak spike in slab moment over a column but distribute it over some slab strip width.

RE: Design of RC Cores

So is this the cross section module in Rapt? Mine always says that it isn't supported in my version or something...

What you're getting at is people should be using an M / Z approach for the whole core as opposed to isolating each panel?

RE: Design of RC Cores

(OP)
Yeah, just seeing people to wrapped up in etabs output. I think the need to be mindful of the real behaviour. Particularly with fe modeling where the meshing can be a little coarse. And the code does talk about group of walls so I think the group should be considered. This approach has happened at a few places I'be been but I prefer to look at the core as a whole.

RE: Design of RC Cores

Trenno,

It would be the Column module that produces M/P interaction diagrams.

RE: Design of RC Cores

Interesting, I'll have to give your method a whirl sometime.

Obviously this relates to RC in-situ cores, I can foresee some issues arise when you start using precast panels stitched together as cores.

RE: Design of RC Cores

(OP)
Oh yeah, I wouldn't even attempt to stitch together precast walls to use as a core for a lateral resisting element.

RE: Design of RC Cores

That's interesting - we do that all the time asixth. As long as you provide plates that can transmit the longitudinal shear in the walls and dowels that can fully develop I don't see the issue. Mind you I still hate precast concrete.

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