Radius Stair Stringer
Radius Stair Stringer
(OP)
I inherited a steel stair design that was using a MC12x10.6 stair stringer. The fabricator already has the stair built and the EOR is requiring the steel stair to be designed by a registered engineer. Well the short story is that I ended up adding a vertical plate to the channel for torsional stifness. I am wondering if anyone could point me in the right direction for determining the correct stitch weld pattern since my stair stringer has axial, shear, torsion, and flexure forces. Please help me in this matter. Thank you.
Val
Val
Val Courtney, PE
Optimal Engineering, Inc.






RE: Radius Stair Stringer
If the axial load is the same as each of the member and it goes into the channel first and you would like the plate to share in that load, then provide end welds to transfer that portion of axial load to be carried by the plate.
For flexure, the flexural shear is a measure of the change in bending along the members length therefore VQ/It should give you the reqired stitch weld along the length. MQ/I will give you the end development.
The shear due to warping of the box section should also be added to the flexure shear since it is in the same direction. Refer to a book like Salmon and Johnson for this calculation.
The torsional shear flow calculation should give you the shear flow around the box section. Note that this is at 90 degrees to the flexure shear so you must combine stresses to obtain the resultant vector. Refer to a book like Salmon and Johnson for this calculation.
Once you break it down into pieces , it should be easier. I hope that helps!
RE: Radius Stair Stringer
RE: Radius Stair Stringer
Val
Val Courtney, PE
Optimal Engineering, Inc.
RE: Radius Stair Stringer
RE: Radius Stair Stringer
Just a question, wouldn't the stringer pans brace the stringers for torson?
RE: Radius Stair Stringer
Steve Braune
Tank Industry Consultants
www.tankindustry.com