Can Precast Plank Brace Steel Columns in Direction Parallel to the Plank Span?

[gramy13]

I'm designing a 9-story hotel using 8" precast hollow-core plank with a 2" topping, spanning to conventional wide flange steel beam lines (that align with unit demising walls) supported by HSS tube columns. The plank will bear over top of the steel wide flange beams. The columns are braced by the steel beams in one direction(perpendicular to the plank spans). I'm trying to figure out if the plank diaphragm will act to brace the HSS columns in the direction where I don't have steel beams framing to the columns (parallel to the plank spans), given that the planks bear over top of the steel beams.

I know that the plank can brace the columns parallel to the plank spans in a DeltaBeam or GirderSlab proprietary steel system where the proprietary steel beams are upset into the plank - essentially bracing the bottom flange of the steel beam and in turn bracing the column in the direction parallel to the plank spans.

For my situation, with the plank bearing on top of the beams, maybe I can add web stiffeners at the beam/column connections to stiffen up the joint, or add clip angles to each side of the columns that get welded to soffit embed plates in the planks (in the direction parallel to the plank spans)?

Please let me know what you think - Thanks!

 

[KootK]

I'm assuming that your beams hit the sides of your columns rather than running over top of them. I would say that your plank can brace the columns. It would go something like this:

1) Plank stay put.
2) Top flange of beam stay put at connection to precast closest to column.
3) Beam acts in cantilevered (from nearest connection) weak axis bending to restrain the top of the column.

I know, it sounds a little sketchy. It takes next to nothing to get the job done however.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.