Stair with First 4 Treads Compensated, Then Normal

[Heftor]

Hello everyone,

I'm trying to model a stair where the first four treads are "compensated" (meaning the nosing is adjusted to fit a specific landing or winder condition), and from the 5th tread onwards, they are standard, equal treads, like the floor plan below.

I'm working in Archicad 28 and using the Stair Tool. I can successfully create the compensated treads and risers by dragging the nodes in the floor plan, but the problem is that the stair's underlying structure remains unchanged, which causes issues for the rest of the flight.

Is the best approach to model this as two separate stair elements? Or is there a way to define a "transition node" within a single stair object where the tread compensation stops and the structure recalculates for standard treads?

Does anyone has any experience in this?

Thanks in advance.

Hector

Operating system used: Windows

[Yves]

A little tip by Noémie shared on the French forum Archi-CADlink

https://youtu.be/8I4PLZBbuUc

[runxel]

Great link, Yves! Beat me to it.

Basically, the a bit unintuitive rule here is that whenever you encounter stairs with winding steps at the landing you have to make sure the "actual" direction (as in running direction, "Laufrichtung" in German) of the beginning tread/riser needs to be perpendicular to it. It's just something you need to internalise, then it comes natural.

So, think from the "inside" out, not from the boundary (which would make this example a straight run) inwards.

It also helps to place some 2D guard rails before hand to figure out the construction.

[Lingwisyer]

Curve your walking line so that it still follows the rules you have set, then trim the edges. Though, given your dimensions, you have a fixed inside and outside tread width? So your walking depth changes?

[Heftor]

Hello All,

I'm following up on a previous tips and video about creating a stair with compensated treads. With your help, I've managed to compensate the treads and risers successfully, and the 2D symbol and the stair's top surface.

However, The structural component of the stair I cannot modify it. It remains shaped as if the stair were still tangent, creating a conflict between the tread-riser and structure.

I see that the base line is still tangent

but when I make it a straight line it unmade the steps 😓

 I'm starting to think the issue might be that my initial tangent curve is too steep or extreme for the Stair Tool to cleanly generate a transition to the straight run.

Has anyone encountered this and found a solution? is there a practical limit to how much you can compensate a tread before the structure fails to follow?

Thank you.

Hector

[Barry Kelly]

The trick is that the path or reference line of the stair remains curved.

That is the single blue line you are adjusting in your image - don't do that.

You need to adjust the 'Boundary' lines.

Select the stair on the other side or you can use TAB to cycle selection.

So you are adjusting the shape of the stair boundaries while actually still having a curved path.

Barry.

[Heftor]

Hi Barry,  

I already did that and the structure boundaries are straight but the steps on the structure are not.

As you can see on the screenshoot below:

Regards, 

Hector

[Barry Kelly]

Try pulling the front node of the reference line to the side so the curve is tangential to the vertical line above.

Barry.

[Heftor]

Hi Barry, 

Indeed, I can change the the line reference to make it tangencial to the vertical line:

but this way i cannot have control where the steps start. Now the orientation is good but the I have 2 extra steps:

and adding a extra part of the estructure.

Regards, 

Hector

[Lingwisyer]

Click on the opposite boundary, you should get two green reference lines which you can edit to change the actual bounds of the stair. The video that Yves linked shows the whole process pretty well.