Building geometry concern 11

[hoshang]

Hi all,
please find the attached thread:
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http://www.tipmaster.com/includes/refinfo.cfm?w=450&h=450')

There are no beams on gridlines D and E other than walls, acting as deep beams and shear walls combined.

The black object is hanging from the cantilevered wall above, which means that forms must be kept in place until the wall above cures.

So the black object is hanging from the cantilevered wall above, does this mean the cantilevered wall above (the dark green one) is acting as a hanger for the cantilever slab below (the cantilever slab at level +4.60) at the same time it acts as bearing wall supporting the cantilever slab resting on it (the cantilever slab at level +8.20)? If so, how it can be modeled in an FEA software?

 

[hoshang]

Hi BAretired,
thanks for your response. Another question as in the image below (written as red text):

 

[BAretired]

hoshang, why the hell don't you answer my other question regarding downsizing? I am getting fed up with answering your questions about a building which will likely never be built.

 

[hoshang]

hoshang, why the hell don't you answer my other question regarding downsizing?

This is the architect's task, not mine. He may downsize or add another basement floor.

I am getting fed up with answering your questions about a building which will likely never be built.

No, the building will be built. It's a time-consuming municipality agreement here.
Another question as in the image below (written as red text):

 

[BAretired]

This is the architect's task, not mine. He may downsize or add another basement floor.

Thank you. I thought you were the prime consultant. We will have to wait for his or her decision.

I consider the two short parts as wall, but after the building is completed, all parts will be tied together with reinforcement, so they will all act as wall. The long sections should be designed as deep beams, with adequate reinforcing into the back span, but the distinction between wall and beam loses significance when the work is completed to the top.

 

[rb1957]

"No, the building will be built. It's a time-consuming municipality agreement here."

We've pointed out "fatal" flaws in the design ("flaw" = failure to meet a requirement, as much as they've been explained to us).

The only way this building is getting built is if either ...
1) they change the requirements, give the building an exemption, or a different interpretation; or
2) they change the design (to satisfy the requirements, and also waste nearly all the time you've spent on it).

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[hoshang]

I consider the two short parts as wall,

The long sections should be designed as deep beams, with adequate reinforcing into the back span,

So, I need to consider two stages of analysis:
1- before the building is completed to the top

Here, the the long sections (deep beams) are bearing on the short parts (walls). Here, I'd assume the deep beams as beams on elastic support, am I missing something?
2- after the building is completed to the top

 

[BAretired]

I don't believe you are missing anything.

 

[rb1957]

Apologies, but why do this ?
why have alternate short walls, which AISI forces each overhang to work in isolation ?
Why not have all the walls overhang and they'd work together, no?
What's happening on the different floorplans (to create alternating walls) ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[hoshang]

Hi BAretired,
what's the difference between the two stages regarding load path?
Sorry for being late.
Other concerns:
How one can figure the support for the main stair knowing that it's recommended previously a wall on grid D and E?

 

[Pinwards]

Just when I thought this thread might finally die, it comes limping back to life. On the positive side, if BA keeps going even I (a lowly site civil) might be able to design a building by the end of this!

#

 

[BAretired]

what's the difference between the two stages regarding load path?

I don't understand your question. Are there just two stages? It seems to me that the stress in the wall changes with each new floor added to the cantilevers. Depending on the sequence of form removal, it is possible to determine with some confidence, the most critical combination throughout the construction period. If in doubt, make it stout.

Other concerns:
How one can figure the support for the main stair knowing that it's recommended previously a wall on grid D and E?

Walls on Grids D and E are likely not the only supports for the main stair. Requirements for fire separation between floors may require a wall on Grid 2. The rectangle between stair flights is part of the 20% "open area", so it could have a bearing wall all around the opening. We have not talked about the material enclosing each of the "open areas".

Until you know the story height of each floor, the stair shape will change. Story heights shown today will change as design progresses, so stair support must wait until later. It is possible that stairs will be precast and moved into position by crane. None of this has been discussed to date.

It is time to address the floor and roof framing plans. The large span between Grid B and C will require careful consideration.

 

[hoshang]

I don't understand your question. Are there just two stages? It seems to me that the stress in the wall changes with each new floor added to the cantilevers. Depending on the sequence of form removal, it is possible to determine with some confidence, the most critical combination throughout the construction period. If in doubt, make it stout.

I meant the stages mentioned in my post on 27 Apr 24 06:52.
1- before the building is completed to the top
Here, the the long sections (deep beams) are bearing on the short parts (walls). Here, I'd assume the deep beams as beams on elastic support,
I suppose the load path here would be such that:
Level +4.60 cantilever slab formwork is kept in place. The long section (deep beam) above 4.60 level is erected. Gravity loads from cantilever slab (bottom of deep beams) will be transferred to deep beams (long sections) in addition to deep beam's self-wight (if Level +4.60 cantilever slab formwork is removed after the deep beam gets the required strength). Run analysis. After level +8.20 floor is poured, the cantilever slab in this floor is supported by the deep beam between levels +4.60 and +8.20 and run analysis. My point: if one keeps Level +4.60 cantilever slab formwork after level +8.20 floor is poured and got required strength, one needs to perform analysis once rather than twice. and so on.
2- after the building is completed to the top
Here what will be different than stage 1?

Walls on Grids D and E are likely not the only supports for the main stair. Requirements for fire separation between floors may require a wall on Grid 2. The rectangle between stair flights is part of the 20% "open area", so it could have a bearing wall all around the opening. We have not talked about the material enclosing each of the "open areas".

The blue one can't be added since it would obstruct the corridor pathway.

 

[rb1957]

I don't know much about buildings, but if those red walls are the "only" structural thing holding that building up, well, that looks kinda "minimal".

The little orange squares are foundations, yes? These are just columns in the car park levels, and structural walls in the above ground floors ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[BAretired]

[ol 1]
[li]I think you have the idea.[/li]
[li]Wasn't talking about the blue one. I was talking about the rectangle with a cross half way between D and E. I interpret that to be part of the "20% open area". If so, it needs a wall around it. That wall could be a stair support if you wish. It would have to extend down to foundation level, which it does not do at this time. In any case, that is for you to sort out as EOR.
[/li]
[/ol]

The little orange squares are foundations, yes?

The little orange rectangles, where shown, are columns. Foundations have not been shown yet. They will likely be either footings or piles.

 

[BAretired]

I was trying to find the minimum turning radius for a parking structure. If the plan view below is considered minimal, we don't have enough room to do a 180 degree turn from the Car-lift to the drive aisle, even after moving the two cars currently blocking the drive aisle to Grid A.

There needs to be some serious discussion with the Architect about parking. Adding another story below ground doesn't cut it.

 

[hoshang]

Wasn't talking about the blue one. I was talking about the rectangle with a cross half way between D and E. I interpret that to be part of the "20% open area". If so, it needs a wall around it. That wall could be a stair support if you wish. It would have to extend down to foundation level, which it does not do at this time. In any case, that is for you to sort out as EOR.

If the wall between D and E could be a stair support, how should it be poured (knowing there exists two landings with five steps between them)? Or one should pour it once and extend dowels into the landings?

 

[BAretired]

Hoshang, you are the EOR,not I. You figure it out. If you can't, retain someone who can.

 

[hoshang]

I think you have the idea.

I think you didn't answer my question on 3 May 24 12:33:

Here what will be different than stage 1?

 

[BAretired]

Nothing of any importance. What do you think will be different than Stage 1?

 

[hoshang]

Nothing of any importance. What do you think will be different than Stage 1?

You mentioned this difference here:

I consider the two short parts as wall, but after the building is completed, all parts will be tied together with reinforcement, so they will all act as wall. The long sections should be designed as deep beams, with adequate reinforcing into the back span, but the distinction between wall and beam loses significance when the work is completed to the top.

So I'm looking for the difference.