Curved Concrete Stairs

[Vinny7]

Hi,

Has anyone any experiance in designing curved concrete stairs (without using finite element analysis software). A point in the right direction would be appreciated especially UK codes.

Thanks.

 

[csd72]

compare to a straight line and design for the eccentricity taken out as torsion.

 

[dik]

Something like this... done without the use of a computer and took me about two weeks before I was happy with it... It's still standing without cracks after 30 years... The contractor did not want to remove the formwork... didn't think it would work...

Dik

 

[jike]

Nice looking stairs dik! I assume that the building is framed concrete. Did you cantilever off the 2nd floor and off the ground floor and just connect the 2 cantilevers with the curved landing? Or some other way?

I always like making stairs look like they have no visible means of support!

 

[dik]

Mostly steel... The upper floor is 3" composite steel deck on steel purlins and girders and the lower floor is a structural concrete slab. It was analysed assuming it acted like a 'y' tilted 90 degrees with a horizontal cross member at the junction of the y and the guard rail beams framing into the ends of this horizontal cross member. Some torsion and non-linear, non-homogeneous differential equations... There is limited vertical load but a significant horizontal tensile force at the upper floor. The base is supported by a single pile. Horizontal force at the base is taken by the structured slab.

One of the two toughest things I've ever designed...

Dik

 

[dik]

Forgot to add... it's about 18' from main floor to upper floor if memory serves... Large shopping centre in Regina, Canada.

 

[J1D]

dik,
Good stuff. Did you re-analyse the stair with the help of computer program, and see how close your calculation was?

 

[civeng80]

very nice work csd72. I like to look at how staircases are supported and sometimes its quite a challenging task.

Very good engineering.

 

[civeng80]

sorry that was meant for dik.

Again well done.

 

[himat42]

Vinny7

Did you look at Reynolds & Steedman Handbook? Also the published another book on BS 8110 Code
These two books would give you a solution to your prblem.

HTS

 

[JrStructuralEng]

what computer program is best to analyze concrete (for limit states, i.e. canada)

Our firm is looking for some software for 2-way slabs and other more complicated concrete design.

Any suggestions?

 

[youngstructural]

Okay, I'll bite... What was the other of the two toughest things you've ever designed Dik?

Quite curious after these magnificent stairs!

(I've walked down them, and admired them, prior to seeing them here... Would give almost anything to see a scan of the structural details!)

Cheers,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[jike]

Here is a concrete stairs that turned 90 degrees with no support under the landing. The lowest run is cantilevered off a footing poured integral with the floor.

 

[hokie66]

No disrespect to the fine work of dik and jike, but in my opinion building stairs like that is a poor use of valuable engineering time and resources. They are "cutesy" architecture, but I am waiting to be heckled for being an old fuddy.

 

[dik]

Yup... but, I hate boxes!

Dik

 

[hokie66]

I do too, but IMHO a little post under the landing would not have detracted. The stair with no apparent support which I do admire is the timber one in a church somewhere in SW USA. Somebody will probably have a reference. I have seen pictures of it, and it is amazing, but then it has a greater power to assist in supporting it.

 

[JKStruct]

Hokie, the church is in Sante Fe, New Mexico. Here's a link to a picture

http://hometown.aol.com/lorgallego/stairs.jpg

 

[csd72]

I saw a few spiral stairs in montreal - they were steel stairs with nothing but 1/4 inch stringers. They worked though.

 

[hokie66]

JKStruct,
That link didn't work for me, but I have it on my list to see if I ever get through Santa Fe. Thanks.