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Skin Priorities must affect both Walls and Slabs

Anonymous
Not applicable
Skin Priorities of Walls must affect Slabs and Beams and vice versa.

This way we could have this section without using extra elements just for intersection clean-ups!

Skin Priorities .gif
20 REPLIES 20
Laszlo Nagy
Community Admin
Community Admin
Barry, can you tell me scenarios where you would need to see that Slab outline? In a Structural plan? (I tend to think on a normal Floor Plan you don't have to.) I am thinking of what could be the solution to those?
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NandoMogollon
Advocate
Barry is right on this: slab edge might not be in the same position in section and floor plan views. But neither it was when slab edge angle conditions were introduced.

Laszlo, in some countries the architects are required to provide the structural engineers a "Slab Edge Plan" for them to follow.

In my opinion, (and I just have a small portion of the whole picture) We still need to be careful with modeling the slab as it should be built, or correct at it's Core, and let Finishes and Intermediate skins fight each other trough this new Priority Based Connections.

I guess I was just excited about getting this "material based priorities" at the core of AC, it makes much more "Virtual Building" sense, it's a sort of Materiality Simulation
Nando Mogollon
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Laszlo Nagy
Community Admin
Community Admin
This Priority Based Intersection works on the principle that structures need to collide or overlap in 3D for the connection to be automatically generated. So I think you can model your Slabs to the size you need for the Slab Edge Plan, and it will normally intersect Walls. This way the Slab contour will be in the right place and the intersection with the Wall will also be generated.

Show me concrete examples and we will see if it can be done.
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Barry Kelly
Moderator
laszlonagy wrote:
Barry, can you tell me scenarios where you would need to see that Slab outline? In a Structural plan? (I tend to think on a normal Floor Plan you don't have to.) I am thinking of what could be the solution to those?
laszlonagy wrote:
So I think you can model your Slabs to the size you need for the Slab Edge Plan
Which is why I said ...
Barry wrote:
Not a problem if you don't need to show the slab extent in plan.
Of course there will be many work-arounds (i.e. model the slab to the actual extents you want to see in plan)
As Nando suggested sometimes we are required to produce a slab layout to show the true extent of the slab.
Also we are thinking here of slabs for floors (which I agree you probably won't show on a floor plan) but they could be floor finishes, benchtops, ceilings, shelves, etc., etc.

I just wanted to point out that the slab outline you see in plan may not necessarily be the same extents that you see in section/3D.

Barry.
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Laszlo Nagy
Community Admin
Community Admin
Can you post an image of a concrete example where you see a potential problem?
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Anonymous
Not applicable
Perhaps this should be put on hold pending the release of AC17. It seems this might change with the new priority and SEO functions.
Barry Kelly
Moderator
This is just something I slapped together - not a real life example.
You can see the extent of the slab (dark blue line) and that is what will show on the floor plan.
However the actual slab in section/3D is trimmed to the inside or the external wall skins - these skins having a stronger priority than the concrete skin in the floor.
The concrete in the wall and the slab blend as they are the same building material in each composite (same priority strength).
The top finishes to the slab are trimmed back even further by the wall finishes on the inside of the wall as they are weaker than the wall skins.

So in plan if you were expecting to see the extent of the slab only go to the inside of the external wall skins you will be saddly disappointed.
Yes you could model it to that point rather than to the outside of the wall (which is what I would do) and the plan would be correct.
So long as you didn't want to show the extent of the floor finishes!

Barry.
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Laszlo Nagy
Community Admin
Community Admin
Can you show me a real life example? Theoretical examples are fine, but what is the point if you never encounter them in real life?

I mean, why would you model the Slab to extend to the outside surface of the Wall when the structure (or any other skin of the Slab) only extends to the outside surface of the Wall core?

Also, saying that those skins have a stronger Intersection Priority than that of the structure is unrealistic. They could be set to be stronger but it is unrealistic.

The rule is: model it as you would build it. In that case the Slab should extend to the outside surface of the Wall core. Then, when you show only Slabs to send the data to the structural engineer, the Slab outline is fine.

About creating the outline of the finishes: is that a common thing an architect needs to do?
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Barry Kelly
Moderator
laszlonagy wrote:
Can you show me a real life example? Theoretical examples are fine, but what is the point if you never encounter them in real life?
I guess this could be a real example but I just made it up for illustration purposes.
I don't work on multi-storey commercial buildings so have no idea (or little idea) what the construction of the composites should be or what would shown or not in plan.
laszlonagy wrote:
I mean, why would you model the Slab to extend to the outside surface of the Wall when the structure (or any other skin of the Slab) only extends to the outside surface of the Wall core?
As I said no I wouldn't but with this feature it is possible to do so.
And I am sure many people will.
laszlonagy wrote:
Also, saying that those skins have a stronger Intersection Priority than that of the structure is unrealistic. They could be set to be stronger but it is unrealistic.
In fact as the slab stops at the external edge of the wall the strength of the external skins seems to have no effect unless the slab is extended beyond the wall edge (see image below).
In this image the wall skins are weaker which is why the slab cuts them but in the first example I showed the wall skins are in fact stronger. But it remains the same even when they are weaker.
Which to me is not very consistent, but this is best left till 17 is released to discuss further if needed.
I am still trying to get my head around these new Building Materials which is where the strength is now set (not in the composite now) - and it now has a range of 0 - 999 rather than 0 - 16.
laszlonagy wrote:
The rule is: model it as you would build it. In that case the Slab should extend to the outside surface of the Wall core. Then, when you show only Slabs to send the data to the structural engineer, the Slab outline is fine.
I agree 100%.
This will negate the need for many of these junctions.
laszlonagy wrote:
About creating the outline of the finishes: is that a common thing an architect needs to do?
Probably not but who knows what some people want to show on their plans?

All I wanted to point out was that with this feature the extent of the slab in the plan view does not necessarily represent what you see in section/3D.
Maybe we should wait untill 17 is released and then I am sure more practical examples will crop up.

Barry.
junctions_2.jpg
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Laszlo Nagy
Community Admin
Community Admin
OK, I get what you are saying.
Probably this is why Graphisoft will have a Modeling Guidelines document which will detail how to model things in ArchiCAD for the best utilization of Priority Based Connections. Beyond that it is up to the user and we know that users sometimes do wild things.

By the way, I tried that connection you attached in your last post and it works fine for me in all cases: both when the Slab extends to and beyond the outside surface of the Wall, and both when the structural concrete is stronger or weaker than those Wall skins.
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