Stair with floating/hanging mid-landing 4

[struggle67]

Hi,

How do I design this type of stair? Please share with me if you have any worked example.

Thank you.

 

[271828]

You'll probably need to build a 3D frame analysis model to determine the member forces and deflections. You'll also want to check vibration per the AISC Design Guide 11.

AISC's Design Guide 34 is on the general subject of stair design.

 

[JLNJ]

Hire a good structural engineer.

 

[dik]

Something like... done about 30 years back...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[struggle67]

Thank Guys

I did a simplified model and compared with my hand calculation results. They are almost the same. My model results are as shown below. Do they look ok? Any comment?
Fig 1 model
Fig 2 minor axis moment
Fig 3 Axial load (Tension @ top stringer and compression @ bot stringer)
Fig 4 Major axis moments.

 

[Tomfh]

You need to consider torsion

 

[dik]

Tom... big time...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Agent666]

You also need to consider how you're going to consider any interstorey drift. There was a thread here a while back on this form of construction and I can't locate it.

https://engineervsheep.com

 

[sticksandtriangles]

Similar thread here:

https://www.eng-tips.com/viewthread.cfm?qid=466727

S&T

 

[dik]

Now you tell me... never considered that...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Agent666]

Managed to find the thread I was thinking of.
Link

https://engineervsheep.com

 

[struggle67]

Thank Agent666

The thread is really helpful.

 

[Bagman2524]

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1624891005/tips/AggieHangingStair_dhrl5n.pdf[/url]

AISC had an article in Modern Steel Construction a while back

All I know is P/A and Mc/I

 

[dik]

and if you push on a rope, you reduce the effective prestress...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[MSUK90]

I did a simplified model and compared with my hand calculation results. They are almost the same. My model results are as shown below. Do they look ok? Any comment?
Fig 1 model
Fig 2 minor axis moment
Fig 3 Axial load (Tension @ top stringer and compression @ bot stringer)
Fig 4 Major axis moments

Have you managed to confirm your calculations with some experienced professional?
How did you considered torsion?
Which program you used for modelling? Isn't using both supports pinned render such structure almost unstable?
I would like to know your detailed calculations and detailing you have done.

 

[struggle67]

HI MSUK90,

Have you managed to confirm your calculations with some experienced professional?

I wanted to. But not yet.

Which program you used for modeling? Isn't using both supports pinned render such structure almost unstable?

Tekla Structural Designer. I consulted with the software support team and I found out that pinned supports render unstable and can not be done in TSD so I referred to the link shared by Agent666 above and thinking to use the two-member truss model suggested by KootK for my hand calculation in the future.

How did you consider torsion?

If I were to use the two-member truss model, my torsion would be due to the eccentricity (up and down stringer offset).

I would like to know the detailed calculations and detailing you have done.

I have not worked out any detail. It is just for my knowledge. In the future when I encounter this type of stair I don't want to say no.

Thanks