"Bent" LVL Stair Stringer with Gusset Plate Connection

[braskan]

Please see the attachment. I originally designed this stringer using steel tube with full penetration welds where the flat landings attach to the sloped stringer. Client is looking to build this "bent" beam using wood. My thought is to go with 2-ply 1-3/4 x 11-1/4 LVL, overlapping at the two turns, then designing a bolted gusset plate connection to create one "continuous" beam. There are no interior supports and the "bent" stringer must span from wall to wall. Any thoughts or reference material I can use for design purposes? Again, please see the attachment for clarification.
Thank you.

 

[COEngineeer]

I did this on one of my project. I think I used 2-11 1/4 lvl also. But, I wanted to make it really tight at the connection so I used steel plate on each side instead. So you can tighten the bolts so that the plates will grab onto the lvl. If you use the plate between the lvl, i dont think it will be a good connection. You will crush the lvl when you tighten the bolts. Also, another issue we had was the bolt heads sticking out. We ended up use another lvl to cover it.

Never, but never question engineer's judgement

 

[braskan]

I've designed 1/4" plates to work on either side of the beam. Now the question is, how many bolts, and how far does the plate need to extend onto each section of LVL BM. Any examples of this bolt/plate design?

 

[COEngineeer]

well.. follow minimum edge distance for steel and wood. Then assume it is a continous beam so you know the moment and shear at the connection. Then just design it like eccentrically loaded bolt group. NDS might have a section about that.

Never, but never question engineer's judgement

 

[structuralaggie]

Use a bent channel for the stringer - moment connections in wood are generally a bad idea.