!Restored: Flaw in stair logic

[Anonymous]

The problems with the stair tool stem from a flaw in the logic. The stairs are being defined by where the riser is rather than where the front edge of the stair tread is.

In this post I've attached an image showing a stair that does not have a nosing overhang:
- the 3D matches the 2D; and
- the handrail is the correct height above the nosing of the stair (as stipulated by regulatory requirements).

In the subsequent post I will attach an image of the same stair with a 30 nosing overhang:
- the 3D no longer matches the 2D; and
- the handrail is no longer the correct height above the stair nosing.

These problems occur because the 3D of the stair is being generated by the outside face of the riser rather than the front edge of the tread. The nosing overhang is being added to the front edge of the tread instead of at the back where it should be, with the riser face moving back by the distance of the nosing overhang.

In the real world stairs are set out by their treads, not the risers, and the locations of all of the other elements of the stair is determined relative to where the treads are located.

I'm really surprised that a program as mature as Archicad 11 contains such a fundamental flaw in its logic. It is not reassuring.

[Anonymous]

Objective
http://www.encina.co.uk/objective.html

[David Shorter]

Whats I find interesting is that this logic flaw goes back (at least) to version 10. Whats even more interesting is that I understand no one has ever reported it before (at least in Australia)

[Steve Jepson]

william235711 wrote:
Steve,

I agree with you and I do it all of the time in BOA but Archicad has serious limitations when modeling in its 3-d window. As one of the plug-in writers has pointed out, you cannot easily rotate anything in 3-d. It's too cumbersome and time consuming.

Archicad needs to improve its 3d capabilities or make the plug-in, I forget the name of the product and the company, part of the package.

What is BOA ?

Stair parts are easy to model with ArchiCAD. What part of the stair would you model in ArchiCAD if it were not so difficult?

Can you show a picture of it?

Something like this model?

[Thomas Holm]

Steve wrote:
What is BOA ?

BOA (now dead) was the heir of Architrion, one of the first 3D CAD programs for personal computers (nee ca 1986, French, Mac only). Google for BOA CAD.

[Anonymous]

Now that 12 is out can anyone tell me if the stair logic flaw is fixed. Or is it still there?

[Anonymous]

I downloaded the demo version of 12 and the flaw in the stair logic is still there. I am finding it very difficult to understand and rationalise:
- How the problem had never been picked up before.
- Why, when its been pointed out to them, that it hasn't been fixed.

[Anonymous]

I do share your frustration with the stair tool.

Here in Greece it's quite common to use a 270degree staircase with no landings, so it's one continuous flight of steps. Needless to say, I have yet to manage to model that kind of staircase in ArchiCad. There is no predefined model for such a type and even if i manually draw it and try creating it from a polyline, it wont allow me to. The only chance i ve had is to join 2 staircases together but that just looks tacky.

Sorry to hijack your thread, just thought i'd post this here since it's staircase problems you're talking about.

[Thomas Holm]

konnos wrote:
Here in Greece it's quite common to use a 270degree staircase with no landings, so it's one continuous flight of steps. Needless to say, I have yet to manage to model that kind of staircase in ArchiCad. There is no predefined model for such a type and even if i manually draw it and try creating it from a polyline, it wont allow me to. The only chance i ve had is to join 2 staircases together but that just looks tacky.

I don't see your problem. This took 5 minutes, with (almost) default settings. Stair spiral 12 from the library and a Stairmaker stair created from scratch.

[Anonymous]

Hehe ye! I forgot to mention it's not a round staircase but rather a rectangular one, any width or length, it doesn't matter.
I used the command Design->Creat Stair using Selection and got the stair plan in the bottom of the image. The stair type on the left was used. (the stair type on the right gives me landings, which i don't want)
It won't let me put it in my plan, as it's saying "try decreasing nosing or extend the winder range". Changing nosings in that menu does not do anything. I m just convinced that ArchiCAD cannot automatically do the staircase i want. I m sure gdl knowledge will come to use for such things, but i don't feel like digging so deep into programming

[Anonymous]

Konnos
It's really bad at what we call winders.
It won't let me build double winder stairs I know are legal (to strict International Building Codes standards), giving me the same old dumb line you get:"try decreasing nosing or extend the winder range" which is feces.
I know damn well what I can build LEGALLY.
Yet it would tell me that the stair in image below is OK. Ha!
Bier