The reference I have is based upon helical poured concrete stairs. This
"Reinforced Concrete Designer's Handbook" by Reynolds and Steedman. I did a
large stair that was straight at the top and had a 110 degree curve at the
bottom for a 10 million dollar home in Bermuda. Floor to floor was almost
14'. I used a frame analysis program for the stringers. It was a little
conservative because it ignored all of the help from the treads and risers,
however, it was good enough. We used a box section fabbed out of plate to
handle the torsion. Seemed to work well. I would doubt that a c12 could
handle the torsion.
At 04:13 PM 6/1/00 -0700, you wrote:
>The stair is 6'-6" wide with outside radius of 13'-6" and inside radius
>7'-0". The stringers are made from C12 and the risers and treads are 12ga
>closed system welded to the stringers.
>The arc is 90 deg.
>Are there design charts or tables that have already been prepared for stairs
>of this type? If not, are there shortcuts to design other than doing a
>finite element anaylsis.
>I'm doing the structural design.
>Thank you for your assistance.
>VE Solutions, Inc.
David Handy, P.Eng.
The Thompson Rosemount Group, Cornwall, Ont. Canada
Opinions expressed are personal only.